Portable moist heat system

ABSTRACT

A portable moist heat delivery system comprising a water vapor generating portion comprising a water vapor source and a heat source; a water vapor-air regulating portion, said water vapor-air regulating portion comprising a water vapor-air mixing layer, and a water vapor-air distribution layer; said water vapor generating portion and said water vapor-air regulating portion being in fluid communication; and said water vapor-air regulating portion having a latent heat delivery surface disposed adjacent said water vapor-air regulating portion which delivers moist heat at a preselected temperature range wherein about 15% to about 95% of the moist heat is latent heat of condensation. Methods include delivering improved pain relief, blood flow, relaxation, and reduced cardiac workload.

This application is a divisional application of U.S. application Ser.No. 12/454,129, now U.S. Pat. No. 8,430,921, filed May 13, 2009, whichclaims the benefit of U.S. Provisional Applications 61/053,480, May 15,2008 and 61/093,009, filed Aug. 29, 2008, each of which is incorporatedby reference herein in its entirety.

FIELD

The present invention is directed to a portable heat delivery system. Inparticular, the present invention is directed a portable heat deliverysystem that generates water vapor and provides moist heat. The presentinvention also includes methods of making the portable heat deliverysystem and methods of providing pain relief, deep muscle heating,increased blood flow, reduced cardiac work, relaxation, wound healing,delivery of moisture, delivery of actives, body warming, respiratoryrelief, skin hydration, enhanced sleep and physical therapy.

BACKGROUND

Disposable heat wraps have become a popular way of applying heat torelieve discomfort of temporary or chronic body aches and pains.Disposable heat wraps typically comprise an exothermic composition forgenerating heat, wherein the exothermic composition typically comprisesmetal powder, salts, and water that allows the exothermic composition torelease heat upon oxidation of the metal powder. Other disposable orreusable devices can use energy produced by neutralization of acids andbases; heat of hydration of inorganic salts; re-heatable gels; andelectrical energy to produce heat. Such devices have been foundgenerally suitable for treatment of aches and pains associated withstiff muscles and joints, nerve pain, back pain, rheumatism, respiratorysymptoms and the like. Such devices usually produce heat but containlittle moisture.

Some disposable heating devices can provide sustained heat for periodsof from about one hour to about twenty-four hours, and are generallydescribed as being less messy and more convenient to use than otherconventional heat sources such as whirlpools, hot towels,hydrocollators, heating pads and elastic compression bands. However,there are advantages to delivery of both heat and moisture, such as by awhirlpool or hot towel. Moist heat is often felt to be more soothing andcomforting, and can deliver heat and pain relief more quickly than dryheat. However, conventional methods of delivering moist heat, such ashot towels and whirlpools, can be cumbersome and inconvenient and aregenerally not portable. In addition, certain methods, such as hot towelsand some current products that claim to deliver steam heat, can onlydeliver heat for a short period of time, sometimes 15 minutes or less.

Various approaches of enhancing exothermic reactions in portable heatwrap devices to provide longer heating duration and/or provide heat andmoisture include the incorporation of various and different carbonmaterials such as activated and non-activated carbon materials into theexothermic compositions. Other approaches include the addition ofwater-retainers or water-holding materials to the exothermic compositionto allow excess water to be present and water vapor to be generated.

Other approaches to produce heating devices that provide heat andmoisture include attempting to regulate the rate and extent of theexothermic reaction, producing water vapor, regulating temperature ofthe water vapor, and insulating the skin of a user against thepotentially skin-damaging temperature of the water vapor. For example,see U.S. Pat. No. 6,629,964 to Ono. However, most known heating methodsand devices for providing heat and moisture provide an inadequate amountof water vapor as the known devices either do not produce an amount ofwater vapor effective to provide sufficient heat and moisture,particularly in deep muscle tissue; or do not produce water vapor for along period of time, generally for less than about 4 to 8 hours, oftenfor less than an hour, and typically for about 15 minutes. Further, suchdevices of the prior art are designed to deliver steam or hot vapor perse.

Further the devices of the known art typically generate water vapor byvaporizing water in an exothermic composition. However, it is known thatthe thermal performance of typical exothermic compositions containingactivated carbon and iron are highly sensitive to and dependent on thewater level in the composition. Specifically, an excess level of waterin an exothermic heat cell can cause a slow rate of heat up. This is dueto water restricting the availability of air needed for the exothermicreaction to occur. Thus, the restriction of air results in slow heatingand very little or no water vapor generation. However, by trying toreduce the water level in such a composition in order to achieve a fastheat up rate, the duration of the exothermic reaction can besignificantly reduced; i.e. the reaction will quickly end because theactivated carbon loses its ability to adsorb oxygen as it dries.

In addition, for a high water vaporization rate, an exothermiccomposition must get quite hot (>65° C.). Moreover, in order to providedeep muscle heating and effective, sustained pain relief in deep muscle,the deep muscle temperature should be above 38° C. However, becausehuman skin can be damaged at elevated skin temperatures believed bythose skilled in the art to be above about 43° C., a heating device mustbe able to keep the skin temperature of a human user below about 43° C.while providing a high amount of heat to the skin and deep muscle. Thus,a moist heat device must protect the skin from the high temperature ofan exothermic composition while delivering high levels of heat, bykeeping the skin temperature below about 43° C.

Therefore, despite advances in technology for providing heat andmoisture, there remains a need for a portable heating device thatprovides rapid water vapor generation and heat up, provides sustainedwater vapor generation, delivers an effective amount of heat to providedeep muscle heating, and maintains the skin temperature below about 43°C.

SUMMARY OF THE INVENTION

The present invention includes a portable moist heat delivery systemcomprising:

-   -   (a) a water vapor generating portion comprising a water vapor        source and a heat source; and    -   (b) a water vapor-air regulating portion, said water vapor-air        regulating portion comprising a water vapor-air mixing layer,        and a water vapor-air distribution layer;    -   said water vapor generating portion and said water vapor-air        regulating portion being in fluid communication; and    -   said water vapor-air regulating portion having a latent heat        delivery surface disposed adjacent said water vapor-air        regulating portion which delivers moist heat at a preselected        temperature range wherein about 15% to about 95% of the moist        heat is latent heat of condensation.

The moist heat delivery system may provide a water vapor-air mixture tothe latent heat delivery surface and, wherein said water vapor-airmixture has a dew point temperature of from about 30° C. to about 50° C.

The present invention also includes providing a therapeutic devicecomprising: a portable moist heat delivery system, the portable moistheat system comprising a water vapor generating portion comprising awater vapor source and a heat source; and a water vapor-air regulatingportion, said water vapor-air regulating portion comprising a watervapor-air mixing layer, and a water vapor-air distribution layer; saidwater vapor generating portion and said water vapor-air regulatingportion being in fluid communication; and said water vapor-airregulating portion having a latent heat delivery surface disposedadjacent said water vapor-air regulating portion which delivers moistheat at a preselected temperature range and about 15% to about 95% ofthe moist heat is latent heat of condensation. The device may be anarticle selected from the group consisting of back wraps, knee wraps,neck wraps, menstrual wraps, joint wraps, hand/wrist wraps, neck-to-armwraps, facial wraps, foot wraps, body wraps, blankets, bandages,multi-purpose wraps, patches, pads and combinations thereof.

The present invention includes providing a therapeutic device in whichthe water vapor generating portion comprises a plurality of water vaporgenerating heat cells, the heat cells comprising a particulateexothermic composition.

The present invention also includes providing a therapeutic devicewherein the heat source comprises a plurality of heat cells at least aportion of said heat cells aligned in a row; and wherein a strip of afoam material overlays said row of heat cells providing an air spaceparallel to said row of heat cells.

The present invention also includes providing therapeutic devicecomprising, (a) a portable moist heat delivery system, said systemcomprising a water vapor generating portion comprising a water vaporsource and a heat source, wherein said water vapor source is waterabsorbed onto a water manager and said heat source is a particulateexothermic composition comprising iron; (b) a water vapor-air regulatingportion, said water vapor-air regulating portion comprising at least onewater vapor-air mixing layer, and at least one water vapor-airdistribution layer, wherein said water vapor-air mixing layer is anaerated structure comprising at least one layer of a material selectedfrom the group of woven materials, non-woven materials and combinationsthereof and said water vapor distribution layer comprises at least onelayer of a foam material; said water vapor generating portion and saidwater vapor-air regulating portion being in fluid communication; andsaid water vapor-air regulating portion having a latent heat deliverysurface disposed adjacent said water vapor-air regulating portion whichdelivers moist heat at a preselected temperature range. About 15% toabout 95% of the moist heat is latent heat of condensation.

The present invention also includes a method of providing a benefit to auser comprising: providing a portable moist heat delivery systemcomprising a water vapor generating portion comprising a water vaporsource and a heat source; and a water vapor-air regulating portion, saidwater vapor-air regulating portion comprising a water vapor-air mixinglayer, and a water vapor-air distribution layer; said water vaporgenerating portion and said water vapor-air regulating portion being influid communication; and said water vapor-air regulating portion havinga latent heat delivery surface disposed adjacent said water vapor-airregulating portion which delivers moist heat at a preselectedtemperature range; applying said system to a surface of a user whereinthe latent heat delivery surface is located proximate the surface of theuser; initiating heating of said system; and transferring moist heat tothe skin of the user at a preselected temperature range, wherein themoist heat is about 15% to about 95% latent heat of condensation.

The devices and methods of the present invention, which provide moistheat, can improve the speed of pain relief, increase deep muscletemperature, increase blood flow, and reduce cardiac work. In addition,the devices and methods of the present invention can aid wound healing,provide body warming, deliver actives, deliver moisture to the skin,provide relaxation, provide respiratory relief, enhance sleep, aid inphysical therapy of the heated area, promote or enhance post-operativerecovery, promote or enhance injury recovery and combinations thereof.The devices and methods of the present invention can also be used forimproved, controllable and uniform application of cosmetic andtherapeutic compositions to and through the skin and mucus membranes.

BRIEF DESCRIPTION OF THE DRAWINGS

The application file contains at least one drawing executed in color.Copies of this of this patent with color drawings will be provided bythe Patent and Trademark Office upon request and payment of necessaryfee.

FIG. 1 is a simplified cross sectional schematic diagram of anembodiment of the present invention.

FIG. 2 is a simplified schematic diagram of an embodiment of the presentinvention.

FIG. 3 is a cross sectional schematic diagram of an embodiment of thepresent invention.

FIG. 4 is a top view of an embodiment of the present invention.

FIGS. 5a and 5b are infrared photographs of an embodiment of anactivated portable moist heat delivery system. FIG. 5a is a view of theexternal surface and FIG. 5b is a view of the latent heat deliverysurface.

DETAILED DESCRIPTION OF THE INVENTION

The present invention includes a portable moist heat delivery systemcomprising: a water vapor generating portion comprising a water vaporsource and a heat source; a water vapor-air regulating portion, thewater vapor-air regulating portion comprising a water vapor-air mixinglayer, and a water vapor-air distribution layer having a latent heatdelivery surface disposed adjacent the water vapor regulating portion.The water vapor generating portion and the water vapor-air regulatingportion are in fluid communication and air and water vapor can flowwithin and between the water vapor generating portion and the watervapor-air regulating portion. The latent heat delivery surface isdisposed adjacent the water vapor-air regulating portion. The latentheat delivery surface of the moist heat system delivers moist heat at apreselected temperature range and about 15% to about 95% of the moistheat is latent heat of condensation. For a portable moist heat systemfor use on human skin the preselected temperature should be atemperature that will not damage or burn the skin preferably below about43° C.

The portable moist heat delivery system of the present inventiondelivers heat safely and quickly to a human body. The present inventionalso includes methods for delivering heat safely and quickly to thebody, methods for providing deep tissue heating, pain relief, woundhealing, reduced cardiac work, relaxation, increased blood flow,delivering moisture, enhanced sleep, physical therapy, and deliveringactives. The devices and methods of the present invention can deliversustained moist heat for up to about 8 hours. The system can be asingle-use disposable system or can be incorporated into a reusable orpartially reusable system.

The portable moist heat delivery system will be described here in thecontext of use with a human body. However, as one skilled in the artwill appreciate, the portable moist heat system and methods describedherein are equally adaptable for use with other animals, plants orinanimate objects recognizing that the maximum temperature of the latentheat delivery surface and the total amount of heat delivered may beadjusted using methods discussed herein to optimize performance for theintended subject. For example, animal body temperatures and sizes maydiffer substantially from those of a human and thus the selectedtemperature range and/or amount of moisture to be converted water vaporand/or the number of heat cells used may need to be varied toaccommodate the physiology and/or anatomy of the selected species.

The invention can comprise, consist of, or consist essentially of theelements and limitations of the invention described herein, as well asany of the additional or optional ingredients, components, orlimitations described herein.

As used herein, “water vapor” refers to water in the gaseous state.“Water vapor-air mixture” and “water vapor-air mixing” refer to addingair to “water vapor” as defined herein. Energy must be added toaccomplish the phase change of changing liquid water to water vapor. Inthe exemplary embodiment discussed herein, heat energy is used. Theenergy added to accomplish the phase change from liquid water to watervapor is latent heat of evaporation. The latent heat of evaporationenergy is released upon on the phase change of condensation of watervapor to liquid water and referred to as latent heat of condensation.The word “steam” as used herein also refers to water in the gaseousstate and the terms water vapor and “steam” may be used interchangeablyherein with the understanding that “steam” refers only to water vapornot a mixture of water vapor and liquid water droplets.

As used herein “dew point” temperature refers to the temperature towhich a water vapor-air mixture must cool before water vapor thereinbegins to condense.

“Humidity ratio” is the ratio of the weight of water vapor to the weightof dry air.

“Latent heat”, as used herein refers to the amount of energy in the formof heat released or absorbed by a substance during a change of phase(i.e. to or from solid, liquid, or gas).

“Moisture”, as used herein refers to water.

“Moist heat”, as used herein refers to heat wherein about 15% to about95% of the transferable heat energy is in the form of latent heat ofcondensation of water vapor. As water vapor and water vapor condensationare associated with moist heat, moist heat includes a moisturecomponent. Moist heat delivery system may also transfer water vapor and,when condensation occurs, and latent heat is released, liquid water. Asa moist heat delivery system may in some embodiments operate inconjuction with a another type of heat delivery system, it should beunderstood that about 15% to 95% of the transferable heat energy in theform of latent heat means for the moist heat delivery system and thatthis level of production of moist heat should be maintained by the moistheat delivery system for at least about 10 minutes, alternatively, forat least 20 minutes, and alternatively, for at least 30 minutes.

A “pre-selected temperature” as used herein may include the statedtemperature plus or minus-1° C. or alternatively plus or minus 2° C., ora maximum temperature (i.e.) a temperature no greater than the statedtemperature) or a temperature range with the understanding that thepre-selected temperature means that the temperature behavior ispredictable and reproducible under the stated conditions.

The terms “active” or “active agent” and “therapeutic agent” may be useinterchangeably herein and include pharmaceutical actives as well assubstances that have desired or beneficial effects such as, for example,cosmetic agents or aromatherapy agents.

The term “surface” as used herein may include a surface per se or alayer of layers of a material(s).

The terms “effective amount” or “therapeutically effective amount” of anactive agent as provided herein is defined as an amount of the agent atleast sufficient to provide the desired therapeutic effect.

-   -   The term “median particle size” means that there are as many        particles that have a size larger than the designated median        size as there are particles that have a size smaller than the        designated median size.

Other definitions are provided as necessary as they occur within thedescription of the invention.

All caliper-measured thicknesses disclosed herein are measured accordingto ASTM Method No. D5729, unless otherwise specified.

All basis weights disclosed herein are measured according to ASTM MethodNo. D3776, unless otherwise specified.

All air-permeabilities disclosed herein are measured according to ASTMMethod No. D737, unless otherwise specified.

All moisture vapor transmission rates (MVTR) disclosed herein aremeasured according to ASTM Method No. E96 unless otherwise specified.

All percentages, parts and ratios are by weight, unless otherwisespecified. All such weights as they pertain to listed ingredients andcomponents are based on the specific ingredient level and, therefore, donot include carriers or by-products that may be included in commerciallyavailable materials, unless otherwise specified.

Moist Heat Delivery System

The physiological benefits of moist heat, such as fast pain relief, deepmuscle heating and increased blood flow can only be achieved if a moistheat device delivers a particular, effective amount of moist heat. Tofacilitate convenient use, it is desirable that a moist heat deliverysystem be portable. The present invention provides for delivery of aneffective amount of moist heat in a portable, convenient, safe moistheat delivery system The portable moist heat delivery system of thepresent invention includes a water vapor generating portion comprising awater vapor source and a heat source; a water vapor-air regulatingportion, the water vapor-air regulating portion comprising a watervapor-air mixing layer and a water vapor-air distribution layer and alatent heat delivery surface. Specifically, the structure is designed toprovide water vapor and air mixing and distribution to provide rapid,safe, efficient and sustained moist heat production and transfer.

A cross sectional schematic diagram of an exemplary moist heat system isprovided in FIG. 1. Referring to FIG. 1, the system comprises a watervapor generating portion 10, and a water vapor-air regulating portion20. The water vapor-air regulating portion 20 comprises a watervapor-air mixing layer 24 and a water vapor-air distribution layer 22.As FIG. 1 shows, the water vapor-air regulating portion 20 is interposedbetween the water vapor generating portion 10 and a latent heat deliverysurface 30. The moist heat delivery system shown in FIG. 1 furthercomprises an external surface layer 40. The external surface 40 islocated proximate to the water vapor generating portion 10 and oppositethe latent heat delivery surface 30.

In one embodiment the water vapor generating portion generates watervapor which is at a temperature of from about 50° C. to about 70° C. Asthe water vapor is formed not only is the water vapor warmed but alsoheat is stored as latent heat of vaporization. In order to generatewater vapor, the water vapor source, must heat quickly and deliver ahigh water vaporization rate for a period of time of at least about 10minutes preferably about 30 minutes or more. The stored heat ofvaporization is released when the water vapor condenses. Water vapor isan ideal candidate to transfer heat because of the magnitude of heattransfer by latent heat when it condenses, and because water vapor iseasily generated and available. In exemplary embodiments describedherein, heat for generating the water vapor is generated using anexothermic thermal composition such as for example an iron based thermalcomposition as disclosed in U.S. application Ser. No. 11/233,916.However, as one skilled in the art will appreciate, other thermalmaterials compositions and/or sources of heat and/or other energysources may likewise be used to generate heat in the practice of theinvention.

In an exemplary embodiment the water vapor generating portion includesthermal composition for generating heat and water available forvaporization. Optionally, these components may be intermixed.

The water vapor-air regulating portion of the moist heat system hasmultiple purposes and functions. The first function is to allowsufficient air to enter the water vapor generating portion to supportthe exothermic reaction. Providing sufficient air to support theexothermic reaction is important because the permeable portion of theportable moist heat delivery system is worn against the body. Tovaporize the water in the exothermic composition, the temperature of thecomposition can be as high as about 70° C. However, because human skincan burn at about 43° C., it must be protected from the hot exothermiccomposition. Thus, in the present moist heat delivery system, as watervapor is generated, it exits the water vapor generating portionthrough/into the water vapor-air regulating portion. As the water vaporpasses through the water vapor-air regulating portion, the water vaporis mixed with air and distributed such that the dew point temperature ofthe vapor-air mixture is lowered to a preselected temperature range. Forgeneral use in humans, this is preferably a temperature that does notharm the skin or other tissue. Conventionally, it is believed that about43° C. or below is a temperature which will not burn the skin. However,it should be recognized that contact of the skin with a high temperaturesource will result in a burn only if the skin is unable to dissipateenergy it receives. Thus, energy transfer as well as temperature isdeterminative of the potential for tissue damage. Typically in dry orconductive heat transfer a burn occurs when the skin temperature exceedsabout 43° C. However, without wishing to be held to the theory, it isbelieved that in the case of moist heat much of the energy istransferred via latent heat of condensation. Thus, the temperature ofwater vapor air mix may be much higher e.g. about 50° C. and the skinwill not burn if the amount of energy transferred by the water vapor isinsufficient and/or transferred at a rate insufficient to elevate theskin temperature above 43° C. and/or dissipated at a rate sufficient tomaintain the skin temperature at about 43° C. or below.

The system of the present invention enables one to use temperatureshigher than about 43° C. without harm to human tissue. Previously it wasthought that the temperature per se of the water vapor exiting a moistheat device must be lowered to less than about 50° C. as measured by adry bulb thermometer or thermocouple in order to prevent skin burns.However, the inventors have discovered that potential for tissue damageand/or energy transfer is not reliably reflected in the temperature asmeasured by conventional dry bulb or thermocouple, but rather is morereliably related to the dew point temperature of the water vapor. Unlikethe dry bulb temperature, the dew point temperature is related to theamount of water vapor in the gas mixture. The dew point temperature isdetermined by the humidity ratio of the water vapor-air mix which is theabsolute level of moisture in the air. The relationship of dew pointtemperature and humidity ratio is that dew point temperature increasesas the humidity ratio increases. The energy content of a water vapor-airmixture is more impacted by the amount of water vapor (i.e. storedlatent heat) than by its dry bulb temperature (i.e. sensible heat). Inregulating the water vapor-air ratio, there may be an incidentaldecrease in the dry bulb temperature of the water vapor-air mixture.However, regulating the dry bulb temperature of the water vapor-airmixture is not required because the energy gained or lost in atemperature change is significantly less than the energy present aslatent heat. Thus, the amount of energy transferred via latent heat canbe controlled by regulating the water vapor to dry air ratio. Such aratio can be expressed as pounds of water vapor/pound of dry air or askg of water vapor/kg dry air.

As an illustration of the importance of regulating dew point temperatureinstead of regulating dry bulb temperature points consider exemplaryconditions A and B in which conditions A and B have the same enthalpy orenergy content but different amounts of water vapor. Condition A is awater vapor-air mixture at its saturation point (maximum water vapor)and has a dry bulb temperature of about 43.3° C. (about 110° F.). Sincethe mixture is saturated the dry bulb and dew point temperatures are thesame. The water vapor-air ratio at condition A is about 0.06 lb watervapor/lb dry air.

Condition B has a lower humidity, or less saturated water vapor-air mixand a water vapor-air ratio of about 0.052 lb water/lb b. In order tohave the same energy content as condition A, condition B needs to be ata significantly higher dry bulb temperature (about 60° C.) thancondition A. The water vapor-air ratio of about 0.052 lb water/lb dryair of condition B corresponds to a dew point temperature of about 40.6°C. When a water vapor-air mixture such as that of condition B contactsthe skin it will not burn the skin at 60° C. since the heat transferrate is very slow. As it contacts the skin the water vapor-air mix willcool down and condense on the skin at about 40.6° C. (about 105° F.). Asit condenses the energy transfer rate will be very high but will notburn the skin since its condensing temperature or dew point temperatureis only 40.6° C. In contrast, the water vapor-air mixture of condition Awill condense on the skin at about 43.3° C. (about 110° F.) and rapidlytransfer its latent heat content. As a result, condition A poses agreater risk of causing skin burn than condition B even though its drybulb temperature is significantly less that that of the water vapor-airmixture at condition B.

Thus, unlike the prior art, the present invention regulates the watervapor-air mixture ratio as opposed to regulating the dry bulbtemperature of a water vapor-air mixture. By regulating the watervapor-air ratio, the condensing temperature or dew point temperature iscontrolled. When the water vapor-air ratio is regulated to less thanabout 0.085 lb water vapor/lb dry air the dew point temperature is lessthan 50° C. Preferably, regulating the water vapor-air ratio to lessthan about 0.060 lb water vapor/lb dry air will lower the dew pointtemperature of the water vapor-air mixture to less than 43° C. One ofthe advantages in controlling the dew point temperature of the moistheat wrap is that the thermodynamics of the system provides atemperature modulation wherein the transfer of latent heat is modulatedby the skin temperature (i.e. the latent heat is transferred at the dewpoint. Thus, transfer will not occur unless the skin temperature is ator below the dew point of the water vapor). This is of particular usefor at risk populations whose skin cannot dissipate heat as well asnormal population due to low blood flow, high fat content and the like.By controlling the dew point temperature to less than 43° C., skin burnsfor the at risk population can be prevented since the transfer by latentheat will stop when the skin temperature reaches the dew pointtemperature.

Thus, in order to avoid skin burn, the amount or ratio of water vapor todry air must be regulated so that the water vapor condenses at atemperature that does not cause harm to the tissue. For human skin, noharm to tissue will occur if the dew point temperature is less thanabout 43° C., for example.

For applications in which a higher dew point temperature is desired,such as for some therapeutic applications, the water vapor air ratio maybe higher. In these applications the skin temperature may still be below43° C. since the inventors have surprisingly discovered that there is asignificant increase in blood perfusion with the use of the moist heatsystem of the present invention. Optionally, a high dew pointtemperature may also be used provided the contact time of the high watervapor-air mix with the skin is short and/or only a portion of the watervapor is allowed to condense at the skin. A short contact time limitsthe amount of water vapor available to contact the skin. Alternatively,the system may be designed such that a portion of the water vapor isdirected to the skin and a portion of the water vapor is allowed toescape the system away form the skin. The contact time and or amount ofthe water vapor-air mix allowed to contact the skin may be influenced bythe wrap design and by the heat cell positions in the wrap.

The portable moist heat delivery system, of the present invention,selectively directs water vapor. In a system intended for human use thewater would be direct toward a user's skin. For human use the watervapor reaching the skin would have a dew point at the desiredtherapeutic dew point temperature of from about 36° C. to about 50° C.,alternatively from about 36° C. to about 45° C., alternatively fromabout 36° C. to about 43° C. alternatively from about 36° C. to about42° C., alternatively from about 38° C. to about 42° C. andalternatively from about 38° C. to about 40° C. The system can directwater vapor to the selected target for a period of from about twentyseconds to about eight (8) hours, alternatively from about twentyminutes to about five (5) hours, and alternatively from about one half(½) hour to about two (2) hours. For human use, the maximum skintemperature and the length of time of maintaining the skin temperatureat the maximum skin temperature may be appropriately selected for aperson needing such treatment such that the desired therapeutic benefitsare achieved without any adverse events such as skin burns. The watervapor-air regulating portion ensures that a therapeutic amount of moistheat is delivered to a user's skin without adverse effects.

The water vapor-air regulating portion of the moist heat system has awater vapor air mixing layer and a water vapor air distribution layer.Further, as a function of the water vapor-air regulator is to adjust theproportion of water vapor to air, the water vapor-air regulating portionmust be in fluid communication with the water vapor generation portionwith water vapor passing freely between the water vapor air generationportion and the water vapor-air regulator portion. In an exemplaryembodiment, the water vapor-air regulation portion is adjacent the watervapor generation portion. Additionally, the water vapor-air regulatingportion needs a supply of air to accomplish the water vapor-air ratioadjustment but as a specific ratio or ratio range is desired regulationof the air supply is desirable. Air supply may be regulated, forexample, by control of the density and/or porosity of the materials usedto construct the system or, alternatively, by the use of channels andapertures in water and/or air impermeable materials.

The interface between the water vapor-air regulating portion and enduser is the latent heat delivery surface. In the case of exemplary humanapplications, this would be the surface of the moist heat deliverysystem that is proximate the human skin. In some embodiments that latentheat delivery surface may contact or partially contact the skin surface.In other embodiments, it may be desirable to have a small air gapbetween the latent heat delivery surface and the skin. In the moist heatdelivery system the generated water vapor is preferentially directedtoward the latent heat delivery surface. The water-vapor may be passedthough the latent heat delivery surface to the user, water-vapor maycondense at the latent heat delivery surface transferring the latentheat energy to the user or, alternatively, a combination of water vaporcondensation and water-vapor transfer may occur.

The terminology of latent heat delivery “surface” has been selected.However, surface is not intended to be limited to any particulargeometric shape, and includes, but is not limited to, planar surfaces,contoured surfaces, and irregular surfaces. The latent heat deliverysurface may comprise a layer of material. Optionally, the latent heatdelivery surface may be integrally attached to the water vapor-airregulator portion, and/or a surface of a portion of the water vapor-airregulator portion. Alternatively the latent heat delivery surface may bea part of a reusable holder for the system, for example.

Water Vapor Generating Portion

The water vapor generating portion of the present invention contains atleast one water vapor source and a heat source. The water vapor sourcecan generate energy and water vapor in any number of ways. Non-limitingexamples of heat sources include by chemical energy; energy produced byneutralization of acids and bases; heat of hydration of inorganic salts;repeatable gels; and electrical energy. Water vapor sources can becombined with a heat source. For example an exothermic heat cell caninclude a mixture of fuel (i.e., heat source) and water and/or waterheld in a water manager, as the water vapor generating portion of amoist heat delivery system. Alternatively, the water and fuel (i.e.,heat source) can be separated with the water being supplied from areservoir or applied to a surface such as the skin and then contactedwith the heat produced by the heat generating source. In water vaporgenerating portions that comprise energy sources that are not compatiblewith water, such as, for example, an electrical element, the energysource can be used to heat separate water-containing elements to producewater vapor. A non-limiting example of a water vapor generating portionuseful in the present invention uses an exothermic composition includingwater in a water manager formed in at least one water vapor generatingheat cell. A moist heat delivery system may contain a single heat cellor a plurality of heat cells. A plurality of heat cells is particularlyuseful in the system of the present invention. A plurality of heat cellsallows for flexible systems of various size and shape. In addition, theuse of a plurality of heat cells allows for an easy control of the watervapor-air mixing ratio for controlling dew point. For example, the dewpoint temperature for a fixed water-vapor mixing and aeration design canbe increased/decreased by increasing/decreasing the number of heatcells. Surprisingly, the inventors also discovered that the duration ofheating and total energy delivered can be controlled by varying thenumber of heat cells used per unit area of water vapor generatingportion. The greater the number of heat cells per area, the longer theduration of heating provided. The fewer number of heat cells per area,the shorter the duration of heat provided. In some embodiments it may bedesirable to use a combination of moist heat delivery systems and othertypes of heat cells such as dry heat cells.

Exothermic Composition

In one exemplary embodiment, the thermal energy for generation of watervapor is provided by an exothermic heat cell comprising a particulateexothermic composition. The exothermic composition comprises a flowableparticulate pre-mix and a brine solution. The exothermic compositionsdisclosed in U.S. patent application Ser. No. 11/233,916, are exemplaryof suitable exothermic fuel composition.

Particulate exothermic compositions have both desirable features andcertain considerations that must be addressed to achieve the desirablefeatures. For example, the performance of an exothermic heat cell can beimpacted by the particle size of the particulate components of theexothermic composition in two main ways. First, variation in particlesize of the particulate components of an exothermic composition can leadto particle separation or segregation within an exothermic composition.Particle size directly affects particle mobility and particulatecomponents can vary in their mobility, resulting in particle separationor segregation. Changes in the exothermic composition due to particlesegregation can lead to less than optimal and/or desired reactionbehavior.

The exothermic compositions defined herein comprise particulatecomponents having defined median particle size ranges such that theexothermic compositions resist particle separation or segregation. It iscontemplated, however, that particulate components having medianparticle size ranges above or below the ranges defined herein aresuitable for use in the exothermic compositions defined herein.

The second way that performance of exothermic heat cells can be impactedby the particle size of the particulate components of the exothermiccomposition is that particle size affects accessibility of air throughthe particulate exothermic composition. In order to support and sustaina vigorous exothermic reaction for releasing water vapor, theparticulate exothermic composition should be porous in order to allowfree access of air to the reactants of the particulate exothermiccomposition. The particulate exothermic composition should be porouseven with initially high water content (for high water vapor generation)and remain porous throughout the reaction. To be and remain porous, theparticulate exothermic composition needs to have an efficient watermanager component and the particle sizes of the components of theexothermic composition should exhibit loose particle packing behavior.Without wishing to be bound to the theory, it is believed that properporosity and maintaining porosity is an important factor in creatingheat cells that have long periods of heat production (i.e., heatproduction for about 8-24 hours) and in creating a composition that hasa consistent, reproducible behavior in a plurality of heat cells.

In one embodiment, the heat cells of the present invention comprise aparticulate exothermic composition that provides for reliable heatingand accordingly reliable and substantial water vapor generation overtime frames of a few minutes to hours when the heat cells areincorporated into portable moist heat delivery systems. The exemplaryparticulate exothermic composition comprises a particulate pre-mixcomposition and a brine solution.

Components of the particulate pre-mix composition may include ironpowder, carbon, absorbent gelling material, and water, which componentsare described in detail hereinafter. Components of the brine solutionmay include a metal salt, water, and optionally a hydrogen gas inhibitorsuch as sodium thiosulfate. The particulate exothermic compositionsdefined herein are generally prepared by constructing the particulatepre-mix composition and rapidly dosing the pre-mix with the brinesolution to result in the formation of the exothermic composition.

For use in a moist heat device a particulate exothermic compositionshould have the ability to provide fast initial heating and also provideheat for a sustained period of time. Typical exothermic heat devicesknown in the Art generally can either provide high levels of heatrapidly but last only a few minutes, or they can provide heat for asustained period of time, but can take up to about 30 minutes to heat.The present invention provides both rapid and sustained heating achievedin part by the choice of components within the particulate exothermiccomposition. By way of non-limiting example, by modifying componentparticle size, the speed of heating, duration of heating and temperatureof the exothermic reaction can be controlled.

By way of illustration, one particular method of modifying theexothermic reaction involves using iron powder having a median particlesize of about 200 μm and an absorbent gelling material having a medianparticle size of about 300 μm, wherein the median particle size ratio ofabsorbent gelling material to iron powder is about 1.5:1. Thisparticular ratio of absorbent gelling material to iron powder providesfor an exothermic composition that exhibits rapid initial heating andwater vapor generation, which has been difficult to achieve withconventional exothermic compositions. Without wishing to be held to thetheory, it is believed that attempts to incorporate a high level ofmoisture in conventional exothermic compositions results in water in theinterstitial particle voids which restricts oxygen flow and slows therate of initial heating. To keep water out of the interstitial particlevoid volume a water manager is often incorporated into exothermiccompositions to absorb excess moisture. However, most water managerssuch as vermiculite and absorbent gelling material have particle sizesthat are significantly larger than the iron particles due to the commonpractice in the art of using very fine iron particles based on thebelief that the iron oxidation reaction is limited by the surface areaof the iron particles. Thus, it has been conventionally believed thatsmall iron particles increase the iron surface area.

However, as the inventors discovered and described in U.S. patentapplication Ser. No. 11/233,916, porosity is an important factor inreaction rate. Thus, the size disparity between the particles of thewater manager and iron can promote particle segregation and tightparticle packing, inhibiting the reaction. For example, when theparticle size ratio of the water manager to iron particles is greaterthan about 7:1, tight particle packing and inhibition of the reactioncan occur.

Thus, with the present invention, exothermic compositions having aparticular median particle size ratio of absorbent gelling material toiron powder are used to achieve the desired packing. The selectedparticle size distribution and ratio facilitates prevention of excesswater in the interstitial particle void volume, and prevention ofparticle segregation and packing with void volumes such that fasterrates of initial heating are achieved. The median particle size ratio ofabsorbent gelling material to iron powder in the present invention isfrom about 10:1 to about 1:10, alternatively from about 7:1 to about1:7, alternatively from about 5:1 to about 1:5, and alternatively fromabout 3:1 to about 1:3.

Iron

It is believed that the exemplary particulate exothermic compositionsdefined herein release heat upon oxidation of the iron powder. There isno particular limit to the purity, kind, size, etc. of the iron powderas long as it can be used to produce heat generation via an oxidationreaction with water and air.

The particulate exothermic compositions of the present inventioncomprise one or more iron powder components at concentrations rangingfrom about 10% to about 90%, alternatively, from about 30% to about 88%,and alternatively, from about 50% to about 87%, by weight of the drypremix composition. Additionally, the system of the present inventioncan comprise greater than about 0.1 g iron powder/cm³ of a heat cell.

Non-limiting examples of suitable sources for the iron powder includecast iron powder, reduced iron powder, electrolytic iron powder, scrapiron powder, sponge iron, pig iron, wrought iron, various steels, ironalloys, treated varieties of these iron sources, and combinationsthereof.

Sponge iron is one source of the iron powder which may be particularlyadvantageous due to the high internal surface area of sponge iron. Asthe internal surface area is orders of magnitude greater than theexternal surface area, reactivity may not be controlled by particlesize. Non-limiting examples of commercially available sponge ironinclude M-100 and F-417, which are available from the HoeganaesCorporation located in New Jersey, USA.

Iron powder having a median particle size of from about 50 μm to about400 μm, alternatively, from about 100 μm to about 400 μm, andalternatively, from about 150 μm to about 300 μm are exemplary of sizessuitable for use herein. Other sizes may likewise be suitable so long asthe ratio of the median particle size of iron to the median size ofabsorbent gelling material is such that the size and distribution ofparticles provides for a particle packing with sufficient void volumesto allow substantially free access of air.

The median particle size of the iron powder, and any other particulatecomponent defined herein, can be determined using a sieve method such asthe method disclosed in ASTM Method B214. Generally, the particles arescreened through a series of sieves consisting of different sizes, andthe weight fraction of particles retained on each screen is measured.The weight fraction of the particles in each screen is then used toconstruct a cumulative weight distribution curve. The cumulative weightdistribution curve is constructed by plotting particle size against thecumulatively added weight percent of particles less than the particlesize retained on the next largest sieve. A median diameter is determinedfrom the cumulative weight distribution curve, wherein the mediandiameter is defined as the particle size that corresponds with 50% ofthe cumulative weight. Details on constructing a cumulative weightdistribution curve is described in “Methods of Presenting Size AnalysisData” in Particle Size Measurement, pages 153-156, 4th Edition, TerrenceAllen, (1990).

Carbon

In the exemplary particulate exothermic compositions of an embodiment ofthe present invention comprise one or more carbon components atconcentrations ranging from about 1% to about 25%, alternatively, fromabout 1% to about 15%, and alternatively, from about 1% to about 10%, byweight of the composition.

Non-limiting examples of carbon suitable for use herein includeactivated carbon, non-activated carbon, and mixtures thereof. The carboncomponent has a median particle size of from about 25 μm to about 200μm, and alternatively from about 50 μm to about 100 μm. Activated carbonis particularly useful. In addition, combinations of the various carbonsare also useful.

Activated carbon is extremely porous in the inner structure giving itparticularly good oxygen adsorption capabilities. In fact, activatedcarbon has the ability to adsorb oxygen extremely well when theactivated carbon is wetted, thus allowing for the activated carbon tofunction as a catalyst in the oxidation reaction. In the presence of ahigh water absorbing material such as for example absorbent gellingmaterial or vermiculite the availability of water to the carbon may berestricted. Thus, it is important that activated carbon be pre-wettedprior to the addition of high water absorbing materials. Without beingbound by theory, it is believed that activated carbon should bepre-wetted because of its inability to compete effectively against thehigh water absorbing material when the particulate pre-mix is dosed withbrine. When activated carbon is pre-wetted, heat of adsorption isreleased such that the water adsorbed by the activated carbon is in athermodynamically low energy state and thus the water does not migratefrom the activated carbon to the high water absorbing material.Therefore, the activated carbon remains wet when the high waterabsorbing material is added, and is able to function as a catalyst foradsorbing oxygen.

In addition to its catalytic behavior, activated carbon may offer theadvantage of serving as an auxiliary water manager for the exothermicreaction and/or adsorb odors such as those caused by the oxidation ofiron powder.

Non-limiting examples of suitable carbons include activated carbonprepared from coconut shell, wood, charcoal, coal, bone coal, and thelike, and combinations thereof are suitable for use herein, but thoseprepared from other raw materials such as animal products, natural gas,fats, oils, resins, and combinations thereof are also useful. There isno limitation to the kinds of activated carbon used. However, thepreferred activated carbon has good oxygen adsorption capabilities. Anexample of a commercially available activated carbon is activated carbonavailable from MeadWestvaco located in Covington, Va., USA.

Additionally, the amount of carbon in the particulate exothermiccompositions defined herein should be minimal in order to maximize theinterstitial particle void volume. Carbon is typically the finestparticle component and excess carbon can result in the carbon filling upthe interstitial particle void volume between the larger particles ofthe other materials. Thus, the amount of carbon needed in an exothermiccomposition for generating moist heat is generally significantly lowerthan that used in conventional exothermic compositions because of therelatively high level of absorbent gelling material used herein.Therefore, the carbon herein is mainly used for its catalytic activityand minimally for its water retention property.

A low level of pre-wetted carbon is also highly desirable for high speedmanufacture of the heat cells of the present invention because a lowlevel of pre-wetted carbon enables the pre-mix to readily absorb thebrine solution. With a high level of carbon, the brine absorption rateis slow due to wetting of the carbon. Thus, a low level of pre-wettedcarbon significantly increases the rate of manufacture of the heat cellsdefined herein.

Absorbent Gelling Material

The particulate exothermic compositions of the present inventioncomprise one or more absorbent gelling materials at concentrationsranging from about 1% to about 25%, alternatively, from about 1% toabout 15%, and alternatively, from about 1% to about 10%, by weight ofthe composition.

The absorbent gelling material (“AGM”) suitable for use herein enablesthe retention of water physically or chemically within the particulateexothermic compositions of the present invention. In particular, theabsorbent gelling material serves the function of storing water forrelease and releasing the water in a controlled manner. Upon heating,stored water is released from the AGM and is converted to water vapor byabsorbing heat, thus, storing heat energy as latent heat of vaporizationin the water vapor. Additionally, a portion of the stored water may beutilized to maintain the activated carbon moisture level. By storingexcess water in the AGM instead of the interstitial particle voidvolume, the exothermic composition in the heat cell is able to rapidlyoxidize the iron and generate an internal temperature high enough toproduce water vapor generated from the water stored in the AGM. Becauseof the AGM's high water holding capacity, the exothermic composition inthe heat cells remains highly reactive over a sustained period of time.While not wishing to be bound by theory, it is believed that the AGM canprevent or inhibit liquid water from entering and/or being maintained inthe interstitial voids of particulate exothermic compounds, therebyfacilitating prevention of “flooding” of the exothermic composition.

Non-limiting examples of suitable absorbent gelling materials includethose absorbent gelling materials that have fluid-absorbing propertiesand can form hydrogels upon contact with water. An example of such anabsorbent gelling material is the hydrogel-forming, absorbent gellingmaterial that is based on a polyacid, for example polyacrylic acid.Hydrogel-forming polymeric materials of this type are those which, uponcontact with liquids such as water, imbibe such fluids and thereby formthe hydrogel. These particularly useful absorbent gelling materialsgenerally comprise substantially water-insoluble, slightly cross-linked,partially neutralized, hydrogel-forming polymer materials prepared frompolymerizable, unsaturated, acid-containing monomers. In such materials,the polymeric component formed from unsaturated, acid-containingmonomers can comprise the entire gelling agent or can be grafted ontoother types of polymer moieties such as starch or cellulose. Acrylicacid grafted starch materials are of this latter type. Thus, specificsuitable absorbent gelling materials include hydrolyzed acrylonitrilegrafted starch, acrylic acid grafted starch, polyacrylate, maleicanhydride-based copolymer, and combinations thereof. The polyacrylatesand acrylic acid grafted starch materials are particularly useful.Non-limiting examples of commercially available polyacrylates includethose polyacrylates which are available from Nippon Shokubai located inChattanooga, Tenn., USA.

The absorbent gelling material has a median particle size of from about300 μm to about 800 μm, alternatively from about 400 μm to about 800 μm,and alternatively from about 500 μm to about 800 μm. Absorbent gellingmaterials having a median particle size of 300 μm or greater have beenshown to contribute to minimal or no particle segregation effects.Reducing segregation effects provides for improved sustained temperaturesuch that the desired therapeutic heat benefits are achieved withoutadverse events such as skin burns. Reducing segregation effects alsoallows for the high-speed production of portable heat delivery devicescomprising a plurality of heat cells and that provide for up to fivehours of moist therapeutic heat.

As described above, the particulate exothermic compositions definedherein have particular median particle size ratios of absorbent gellingmaterial to iron powder. It has been found that exothermic compositionscomprising the defined select median particle size ratios of thesecomponents exhibit minimal or no segregation effects which result inexothermic compositions that meet the intended thermal behavior for thedesired therapeutic moist heat benefits.

In addition to the absorbent gelling material, the particulateexothermic compositions of the present invention can optionally compriseother water-holding materials that have capillary function and/orhydrophilic properties. These optional water-holding materials can beincluded in the particulate exothermic compositions at concentrationsranging from about 0.1% to about 25%, alternatively from about 0.5% toabout 20%, and alternatively from about 1% to about 15%, by weight ofthe composition. Non-limiting examples of such optional water-holdingmaterials include vermiculite, porous silicates, wood powder, woodflour, cotton, paper, vegetable matter, carboxymethylcellulose salts,inorganic salts, and combinations thereof. Absorbent gelling materialand optional water-holding materials are further described in U.S. Pat.Nos. 5,918,590 and 5,984,995.

Metal Salt

The particulate exothermic composition of the present inventioncomprises one or more metal salts at concentrations ranging from about0.5% to about 10%, alternatively, from about 0.5% to about 7%, andalternatively, from about 1% to about 5%, by weight of the composition.

Non-limiting examples of metal salts suitable for use herein includethose metal salts that serve as a reaction promoter for activating thesurface of the iron powder to facilitate the oxidation reaction with airand provide electrical conduction to the exothermic composition tosustain the corrosive (i.e., oxidative) reaction. In general, severalsuitable alkali, alkaline earth, and transition metal salts exist whichcan be used, alone or in combination, to sustain the corrosive reactionof iron.

Non-limiting examples of suitable metal salts include sulfates,chlorides, carbonate salts, acetate salts, nitrates, nitrites, andcombinations thereof. Specific non-limiting examples of sulfates includeferric sulfate, potassium sulfate, sodium sulfate, manganese sulfate,magnesium sulfate, and combinations thereof. Specific non-limitingexamples of chlorides include cupric chloride, potassium chloride,sodium chloride, calcium chloride, manganese chloride, magnesiumchloride, cuprous chloride, and combinations thereof. Cupric chloride,sodium chloride, and mixtures thereof are particularly useful metalsalts. An example of a commercially available sodium chloride includesthe sodium chloride available from Morton Salt located in Chicago, Ill.(USA).

Water

The particulate exothermic compositions of the present inventioncomprise water at concentrations ranging from about 1% to about 50%,alternatively, from about 1% to about 35%, and alternatively, from about5% to about 33%, by weight of the composition. Water suitable for useherein can be from any appropriate source, non-limiting examples ofwhich include tap water, distilled water, deionized water, or anymixture thereof.

It is known that the thermal performance of exothermic heat cells ishighly sensitive to moisture level with a small amount of water givingonly short time of reaction and too much water slowing the desiredheating rate and/or “flooding” the heat cell and terminating thereaction. In a device that generates moist heat, the challenge is evengreater as a supply of water is needed to create the water vapor ofmoist heat. It has been found, however, that the particulate exothermiccompositions with interstitial spaces formed by selection of size anddistribution of particle sizes of iron and AGM of the present inventionnot only provide heat cells that are highly effective in generating highamounts of water vapor exceeding 0.25 grams of water vapor per cell overthe course of the reaction, but also provide heat cells that have fastinitial heating times to achieve desired temperatures quickly. This isachieved by incorporating a sufficient weight ratio of water toabsorbent gelling material such that the particulate exothermiccompositions have high internal water retention (preferably with the AGMacting as the principal repository) and high interstitial particle voidvolumes. The particulate exothermic compositions of the presentinvention comprise a weight ratio of water to absorbent gelling materialof from about 3:1 to about 9:1, and alternatively, from about 4:1 toabout 7:1, by weight of the exothermic composition.

The particulate exothermic compositions of the present invention cancomprise a high level of water and yet be constructed at lower cellweight levels than current heat cells. Therefore, the exothermiccompositions of the present invention are utilized more effectively withhigh water concentration, and less exothermic composition is needed toachieve the desired amount and duration of water vapor generation.

Optional Components

The exothermic compositions of the present invention can furthercomprise one or more optional components known or otherwise effectivefor use in exothermic compositions, provided that the optionalcomponents are physically and chemically compatible with thecompositional components described hereinabove, or do not otherwiseunduly impair product stability, aesthetics, or performance.

Optional components suitable for use herein include materials such asagglomeration aids for agglomeration of particles, non-limiting examplesof which include corn syrup, maltitol syrup, crystallizing sorbitolsyrup, and amorphous sorbitol syrup; dry binders, non-limiting examplesof which include microcrystalline cellulose, microfine cellulose,maltodextrin, sprayed lactose, co-crystallized sucrose and dextrin,modified dextrose, mannitol, pre-gelatinized starch, dicalciumphosphate, and calcium carbonate; oxidation reaction enhancersnon-limiting examples of which include elemental chromium, manganese,copper, and compounds comprising said elements; hydrogen gas inhibitors,non-limiting examples of which include inorganic and organic alkalicompounds, and alkali weak acid salts, specific non-limiting examples ofwhich include sodium thiosulfate, sodium sulfite, sodium hydroxide,potassium hydroxide, sodium hydrogen carbonate, sodium carbonate,calcium hydroxide, calcium carbonate, and sodium propionate; fillersnon-limiting examples of which include natural cellulosic fragmentsincluding wood dust, cotton linter, and cellulose, synthetic fibers infragmentary form including polyester fibers, foamed synthetic resinssuch as foamed polystyrene and polyurethane, inorganic compoundsincluding silica powder, porous silica gel, sodium sulfate, bariumsulfate, iron oxides, and alumina; anti-caking agents non-limitingexamples of which include tricalcium phosphate and sodiumsilicoaluminate; and mixtures thereof.

Such components also include thickeners, non-limiting examples of whichinclude cornstarch, potato starch, carboxymethylcellulose, andalpha-starch; and surfactants, non-limiting examples of which includeanionic, cationic, nonionic, zwitterionic, and amphoteric surfactants.Still other optional components can be included within the compositionsor systems herein, as appropriate, including extending agents,non-limiting examples of which include metasilicates, zirconium, andceramics, and mixtures thereof. The optional components can be includedin the particulate exothermic compositions at concentrations rangingfrom about 0.01% to about 35%, and alternatively from about 0.1% toabout 30%, by weight of the composition.

Oxygen is necessary for the oxidation reaction to occur. However, in theexemplary embodiments presented herein an internal oxygen source is notrequired. Optionally, in other embodiments within the scope of thisinvention, oxygen-producing chemical material may be incorporated in theparticulate exothermic composition at the time of preparation thereof.Non-limiting examples of oxygen sources suitable for use with thepresent invention include air and artificially made oxygen of variouspurity. Air is particularly useful because it is convenient andinexpensive.

Heat Cells

The heat cells of the water vapor generating portion of the presentinvention can comprise particulate exothermic compositions that utilizean exothermic iron oxidation reaction system to provide a water vaporsource. A heat cell comprised of a particulate exothermic compositionand used as a water vapor source to deliver moist heat should have aparticulate exothermic composition capable of remaining highly reactiveeven with high water content. High water content provides high rate ofwater vapor generation for an extended period of time. The particulateexothermic composition provides rapid water vapor generation whenincorporated into a water vapor generating portion of portable moistheat delivery systems. The water vapor generation portion is incommunication with the water vapor-air regulation portion which adjuststhe dew point of the water vapor to a preselected temperature byregulating the proportion of water vapor and air in the water vapor airmixture. For human use the preselected dew point temperature ispreferably one that will not harm the human tissue.

The exothermic compositions of the present invention are particulateexothermic compositions. As used herein “particulate” refers to separateparticles contained within the compositions. The particulate exothermiccompositions defined herein contain separate particles wherein eachparticle has a median particle size ranging from about 25 μm to about800 μm. A range of particle sizes is preferred to yield a compositionwith interstitial pore space.

In an exemplary embodiment, an exothermic composition is prepared bypreparing a premix of wetted carbon iron and AGM which is subsequentlytreated with a brine solution. In one exemplary embodiment thecomposition comprises from about 10% to about 90% by weight of ironpowder; from about 1% to about 25% by weight of a carbon selected fromthe group consisting of activated carbon, non-activated carbon, andmixtures thereof; from about 1% to about 25% or alternatively about 2%to about 12% by weight of an absorbent gelling material; and from about1% to about 50%, alternatively from about 1% to about 35% oralternatively from about 15% to about 35% by weight of water. Anexemplary single heat cell of the present invention can comprise fromabout 0.4 g of pre-mix per cell to about 2.5 g of pre-mix per cell, andfrom about 0.4 g of brine solution per cell to about 1.5 g of brinesolution per cell. A heat cell of the present invention can comprise atotal cell weight, per cell, of from about 0.8 g to about 10.0 g,alternatively from about 1.5 g to about 3.5 g, and alternatively fromabout 2.5 g, to about 3.0 g. In an exemplary embodiment, of a moist heatdelivery system a plurality of heat cells may be used for constructing asystem.

As described above, selection of the particle size of the particulatecomponents particularly the iron and AGM of exothermic compositions isimportant for minimization of particle separation or segregation withinan exothermic composition. Particle size directly effects particlemobility and particulate components can vary in their mobility resultingin particle separation or segregation. The exothermic compositionsdefined herein preferably comprise particulate components having definedmedian particle size ranges such that the exothermic compositions resistparticle separation or segregation.

It is contemplated, however that particulate components having medianparticle sizes ranges above or below the ranges defined herein aresuitable for use in the exothermic compositions defined herein.

The heat cells of the present invention are small compared to mostconventional commercial heat cells, as particle size selection minimizesthe need for excess levels of exothermic composition to compensate forparticle segregation effects. As described above, particle segregationeffects are reduced in the particulate exothermic composition of thepresent invention by using iron powder in a particular ratio withabsorbent gelling material. Further, without being bound by theory, itis believed that the oxidative reaction rate of such exothermiccompositions is controlled by the porosity of the exothermiccomposition. The accessibility of oxygen through the particulateexothermic composition is affected by the packing behavior of theparticles, i.e. the interstitial void volume, and by the amount of waterpresent in the exothermic composition. The particle packing behavior isat least in part determined by the relative particle sizes and thedistribution of sizes of the particles.

In an exemplary embodiment, the heat cell is formed in a unifiedstructure comprising at least two opposed surfaces, preferably, onesubstantially non-air-permeable and non-moisture-permeable surface, suchas a film layer substrate material and one aerated surface that ishighly air-permeable and moisture-permeable, such as a polymer non-wovenmaterial. To direct water vapor toward the skin, the air and moisturepermeable side of the heat cell is disposed toward the latent heatdelivery surface side of the moist heat delivery system. In oneembodiment, the air and moisture permeable surface is interposed betweenthe between the heat cell and the water vapor-air regulating portion ofthe moist heat delivery system and the water vapor-air regulatingportion is interposed between the heat cell and the latent heat deliverysurface. The substantially non-air-permeable surface may either be theexternal surface or oriented proximate the external surface.

Uniform heating and water vapor generation may be provided by using aplurality of heat cells. By using a plurality of heat cells, the size ofan individual heat cell can be reduced. The relatively small size of theheat cells and their spacing in the system of the present inventionenable even air flow to the heat cells. In addition, the water vaporgenerated can be controlled by the number of heat cells used, and theirspacing. By way of non-limiting example, in one exemplary embodiment,two portable heat delivery systems of the same size and composition(e.g. the same in all respects except number of heat cells and thespacing between the heat cells), a system made with 24 heat cells had awater vapor generation rate that was less than two times the water vaporgeneration rate of a system made with 12 heat cells, yet lasted fourtimes as long. Without being bound by theory, the non-linear water vaporgeneration and duration relationship is believed to be due to the fixedsurface area of the system that is accessible to air. Thus, reactionrate, water vapor generation rate and duration of heat generation can becontrolled by the number of heat cells used and their spacing within agiven area.

The Aerated Surface

The aerated surface of the heat cells (e.g. “aerated heat cell surface”)can serve a dual function of providing air to the particulate exothermiccomposition in the water vapor generating portion and preventing theparticulate exothermic composition from leaking out of the heat cell, aswell as forming a water vapor-air mixing layer as part of the watervapor-air regulating portion. The aerated surface impacts regulation ofmixing of water vapor and air, particularly when the system is used in avertical orientation against the skin as the aerated surface is orientedtowards the skin in an exemplary embodiment. Variation of the aeratedskin-facing surface can thus be used to regulate the amount of air mixedwith the generated water vapor to help lower the dew point temperatureof the water vapor-air mixture. However, because of its high airpermeability the aerated surface has no limiting effect on the reactionrate, and particularly the water vapor generation rate, of the system.

The aerated heat cell surface can be formed of an SMMS(spunbond-meltblown-meltblown-spunbond) material, a SMS(spunbond-meltblown-spunbond) material, a spun-bond material, amelt-blown material, mesh, woven fabric and combinations thereof thatcan vary in basis weight from about 15 gsm (grams per square meter) toabout 90 gsm, and alternatively from about 15 gsm to about 76 gsm. In anSMMS material, the “S” layers in the structure provide strength and airentry, while the two “M” layers are made of much finer denier filamentsthat function to prevent the smaller carbon particles from leaking outof the cells. Non-limiting examples of suitable materials used for anSMMS layer include polypropylene, polyethylene, polyester or othersuitable polymer materials known to those skilled in the art.

The aerated heat cell surface can have an air-permeability of greaterthan about 25 cm³/cm²/sec and can have a moisture vapor transmissionrate greater than about 5,000 g/m²/24H. The aerated surface can have athickness of from about 0.05 mm to about 1 mm, alternatively from about0.1 mm to about 0.8 mm, and alternatively of about 0.4 mm

The Opposed Surface of the Heat Cell

The opposed, non-air or semi-air permeable/non-moisture or semi-moisturepermeable surface of the heat cell can be made of films or filmslaminated to non-woven fabrics to form a film layer substrate. Ingeneral, suitable films are those having heat sealability and arecapable of being easily thermally fused. Non-woven materials, if used,provide support and integrity to the film layer substrates. Non-limitingexamples of suitable films include polyethylene, polypropylene, nylon,polyester, polyvinyl chloride, vinylidene chloride, polyvinylidenechloride, polyurethane, polystyrene, saponified ethylene-vinyl acetatecopolymer, ethylene-vinyl acetate copolymer, natural rubber, reclaimedrubber, and synthetic rubber, and combinations thereof. The film layersubstrate has a thickness in the range of about 1 to about 300 μm can benon-air to semi-air permeable and non-moisture tosemi-moisture-permeable. For non-woven fabric, if used, those havingpreferred characteristic properties of light weight and high tensilestrength, e.g., nylon, rayon, cellulose ester, polyvinyl derivatives,polyolefins, polyamides, or polyesters, are suitable.

A non-limiting example of a preferred non-woven material is a SMMSlaminated structure of from about 15 gsm to about 100 gsm (grams persquare meter) basis weight. Such non-woven materials are generallydescribed in Riedel “Nonwoven Bonding Methods and Materials”, NonwovenWorld, (1987). An example of a commercially available non-woven sheet ismaterial number W502FWH, which is commercially available from FQN (FirstQuality Nonwoven)) located in Haxie Township, Pa., U.S.A.

Non-limiting examples of useful film layer substrates includepolypropylene non-woven sheets laminated to a film ofpoly(ethylene-vinyl acetate) or low-density polyethylene (LOPE) having athickness of from about 5 μm to about 100 μm. An example of acommercially available polypropylene/ethylene vinyl acetate (PP/EVA)film is material number DH245, which is commercially available fromClopay Plastics of Cincinnati, Ohio U.S.A.

The heat cell can be formed by bonding opposed surfaces of the aeratedsurface material and the non/semi-permeable film together around theirperiphery thereby forming a pouch, envelope, or pocket. Pockets can alsobe made in the non/semi-air and non/semi-moisture permeable substrate byvacuum, thermoforming, mechanical embossing, vacuum embossing, or otheracceptable means. Preferred for use herein is thermoforming which isdescribed in “Thermoforming”, The Wiley Encyclopedia of PackagingTechnology, pp. 668-675 (1986), Marilyn Bakker, Ed.

When filled with a particulate exothermic composition, each heat cellhas a fill volume, void volume, and a cell volume. The fill volume, asused herein, means the volume of the particulate composition in thefilled heat cell. The void volume, as used herein, means the volume ofthe cell left unfilled by the particulate composition in a finished heatcell, measured without differential pressure in the heat cell andwithout additional stretching or deformation of the substrate materials.The cell volume, as used herein, means the fill volume plus the voidvolume of the heat cell. The ratio of fill volume to cell volume is fromabout 0.7 to about 1.0, alternatively from about 0.75 to about 1.0, morealternatively from about 0.8 to about 1.0, alternatively from about 0.85to about 1.0, and alternatively from about 0.9 to about 1.0.

A heat cell can also be measured in terms of height or thickness of theheat cell at the point of greatest thickness. In an exemplary embodimentthe thickness of a heat cells at the point of greatest thickness is fromgreater than about 0.2 cm (centimeters) to about 1.0 cm, preferably fromgreater than about 0.3 cm to about 0.9 cm, alternatively from about 0.4cm to about 0.8 cm, and alternatively from about 0.5 cm to about 0.7 cm.

The resulting heat cell can have any geometric shape, e.g., disk,triangle, pyramid, cone, sphere, square, cube, rectangle, rectangularparallelepiped, cylinder, ellipsoid and the like. The shape of the heatcell can be elongated in its geometry, with the long axis parallel tothe substrates, having a height of from about 0.2 cm to about 5 cm,alternatively from greater than about 0.5 cm to about 1 cm, a width offrom about 0.2 cm to about 20 cm, alternatively from about 5 cm to about10 cm, and a length of from about 1 cm to about 20 cm, alternativelyfrom about 5 cm to about 10 cm, resulting in a cell volume of from about0.04 cm³ to about 30 cm³, and alternatively from about 1.25 cm³ to about10 cm³.

Alternatively, the shape can be a disk shaped geometry having a celldiameter of from about 0.2 cm to about 5 cm, of from about 1 cm to about4 cm, alternatively from about 2 cm to about 3 cm, and a height of fromabout 0.2 cm to about 1 cm, alternatively from about 0.3 cm to about 0.9cm, alternatively from about 0.4 cm to about 0.8 cm, and alternativelyfrom about 0.5 cm to about 0.7 cm, resulting in a cell volume of fromabout 0.0045 cm³ to about 20 cm³, alternatively from about 0.2 cm³ toabout 1 cm³.

The heat cell can have a planar view surface area, per cell, of fromabout 0.03 cm² about 20 cm², alternatively from about 0.1 cm² to about20 cm², and alternatively from about 1 cm² to about 20 cm². Heat cellswith this area per cell are easily incorporated into flexible deviceswhich provide improved conformity with body forms; provide even, uniformheat to a target area; and improve wearer comfort.

The heat cell can have a pre-mix weight of from about 0.4 g of pre-mixper cell to about 2.5 g of pre-mix per cell, alternatively from about1.0 g of pre-mix per cell to about 2.4 g of pre-mix per cell, andalternatively from about 1.5 g of pre-mix per cell to about 2.3 g ofpre-mix per cell. Heat cells with this weight of pre-mix per cell arealso easily incorporated into flexible devices and systems which provideimproved conformity with body forms; provide even, uniform heat to atarget area; and improve wearer comfort.

In one exemplary embodiment of the moist heat system, a plurality ofheat cells are used. All of the heat cells may be moist heat generatorsor a component of a moist heat generator, or alternatively a portion ofthe heat cells may be moist heat generators or component of moist heatgenerators used in combination with dry heat cells.

In an exemplary moist heat wrap comprising one or more moist heatdelivery systems in which the water vapor source is incorporated intoheat cells, the water vapor source may comprise a planar area from about25% to about 90%, alternatively from about 25% to about 75%, andalternatively from about 25% to about 60% of the total planar area ofthe wrap.

Water Vapor-Air Regulating Portion

The moist heat delivery system of the present invention contains a watervapor generating portion as described above. The water vapor generatingportion preferably selectively directs water vapor toward the watervapor-air-regulating portion. As described above in an exemplaryembodiment this may be accomplished using a permeable film on one sideof the water vapor generating device and an impermeable film on theother side of the water vapor generating device. The water vapor-airregulator portion provides for adjustment of dew point temperature. Thewater vapor generating portion is in fluid communication with the watervapor-air regulating portion and reduces the dew point temperature ofthe water vapor-air mixture exiting the system to a safe temperature fordelivery of latent heat to the target user. In the embodiments describedherein fluid communication is achieved via a permeable material such asa film or other permeable material. However, as one skilled in the artwill appreciate other arrangements which afford fluid communication suchas, for example, channels or apertures may be likewise suitable tofacilitate fluid communication.

Optionally, the water vapor-air regulating portion may orient watervapor generated by the water vapor generation portion towards the latentheat delivery surface and ultimately the user target. In the case ofhuman therapeutic and beauty applications this means toward a bodysurface of the user. It is preferable that the latent heat deliverysurface either be comfortably held against skin or alternatively heldvery near the skin with a controlled and preselected amount of gapbetween the surface and the skin. Accordingly the moist heat deliverysystem may be held in place by being adhesively adhered to the skin, oralternatively placed in a holder such as, for example, a pocket, a wrap,or a contoured device that is held in place at least partially byconforming to a body surface contour. The holder may hold the watervapor generation portion and/or water vapor-air regulating portion inplace against the desired body part. In one exemplary embodiment thewater vapor-air regulating portion or alternatively a portion of thewater vapor-air regulating portion is included in the structure of theholder. The holder may be a single use disposable holder or a reusableholder. The holder may be held in place by any of a variety of meansknown in the art including, but not limited to, adhesives, fasteners,ties, interlocking parts, buttons, snaps or combinations thereof.

In an exemplary embodiment, the water vapor-air regulating portion cancomprise at least one water vapor-air mixing layer and at least onewater vapor-air distribution layer. The layers are arranged such thatwater vapor and air can pass among and between the layers and the watervapor generating portion. The water vapor-air regulating portion alsocan facilitate an even flow of air into, and water vapor out of, thewater vapor generating portion, particularly when the system is used ina manner that compresses the system. To minimize the effect ofcompression it is desirable to use a water vapor mixing layer that isresistant to compression. An example of such a material is a needlepunched non woven material. The water vapor-air regulating portion canalso comprise one or more latent heat delivery surfaces. The latent heatdelivery surface may be a surface per se of a portion of the watervapor-air regulating portion or alternatively comprise a layer or layersof material.

The air permeability of the water vapor-air regulating portioncomprising the water vapor-air mixing layer, the water vapor-airdistribution layer and latent heat delivery surface is from about 25cm³/cm²/sec to about 8000 cm³/cm²/sec, alternatively from about 300cm³/cm²/sec to about 8000 cm³/cm²/sec, and alternatively from about 500cm³/cm²/sec to about 7000 cm³/cm²/sec, measured using ASTM Method No.D737. The moisture vapor transmission rate of the water vapor-airregulating portion is from about 500 g/m²/24 H to about 2,500 g/m²/24 H,alternatively from about 1,000 g/m²/24 H to about 2,000 g/m²/24 H, andparticularly greater than about 1400 g/m²/24 H, as measured using ASTMMethod No. E96. In an exemplary embodiment the water vapor-airregulating portion may comprise one or more water vapor-air mixinglayers and one or more water vapor-air distribution layers.

In one exemplary embodiment, a particularly useful arrangement is to usea single water vapor air distribution layer and a single water vapor-airmixing layer. In this embodiment the moist heat system is incorporatedinto a moist heat wrap and/or pack. It is critical that the perimeter ofthe moist heat wrap or pack is heat sealed so that the perimeter of thesingle water vapor air distribution layer and the single water vapor-airmixing layer of the moist heat system are sealed within the perimeter ofthe moist heat wrap pack. In a preferred embodiment the water-vapor airdistribution layer may be constructed of a foam material in which thebase material of the foam is substantially impermeable to air and watervapor but which has channels and/or apertures which allow passage of airand for water vapor. The water vapor air distribution layer comprising aperforated foam layer heat sealed around the perimeter restricts airfrom coming into the perimeter of the moist heat wrap. As a result, thesize and number apertures and/or channels in the water vapordistribution layer acts to regulate the system by allowing sufficientair for generating the water vapor while also allowing the exiting watervapor to easily move out of the wrap toward the skin thus regulating thereaction rate and in turn the amount of water vapor generated. Byregulating the amount of water vapor generated, the water vaporregulating portion of the wrap can be simplified. Moreover, forembodiments using thermal cells, regulation of the amount of air forreaction also facilitates the control of the heating of the heat cellsso that the cells do not reach an excessively high temperature. In oneexemplary embodiment, only a single layer of 1/32 inch foam was neededto allow for both good moist heat production and transfer performanceand for safe handling of a replaceable moist heat pack with the handsfor removal of the pack from air tight packaging which initiatesactivation and installation into a reusable heat wrap or holder. A thinmoist heat pack that is convenient to handle is desirable for use in asemi-durable moist heat wrap or other semi-durable moist heat devicesince it allows for safe handling of the disposable moist heat pack andconvenient reuse of a portion of the wrap.

In one exemplary embodiment, a particularly useful arrangement is to usetwo water vapor-air mixing layers and two water vapor-air distributionlayers, alternating between the two, with the first water vapor-airmixing layer adjacent the water vapor generating portion. Alternativelya water vapor-air distribution layer can be placed adjacent the watervapor generating portion. Optionally, as described above, a water vaporair mixing layer can also be physically formed in integral associationwith the water vapor generating portion.

The system of the present invention is designed to allow an exothermicwater vapor source to operate at a high temperature, from about 50° C.to about 70° C., to maximize water vapor production while deliveringlatent heat and moisture to the user at a selected temperature for ahuman use. For a human user the selected temperature is typically atemperature that does not harm the skin. As water vapor and thecondensation of water vapor to release latent heat are important to theenergy transfer in a moist heat system, the pre-selected temperature forthe moist heat system in a preferred embodiment is the dew pointtemperature of the water vapor-air mixture proximate the latent heatdelivery surface. In exemplary embodiments for human use the dew pointtemperature may be about 45° C., or alternatively about 43° C., oralternatively about 40° C. wherein about includes temperature varying by+/−1° C. or alternatively by +/−2° C. Thus, the system providesprotection from thermal damage to the user and maintains an ideal watervapor generating environment that stores and subsequently releases heatenergy.

The inventors have surprisingly discovered that dew point temperatureshigher than about 43° C. may be used in some instance without harmingthe human tissue. It is believed, without wishing to be held to thetheory, that this is possible because sufficient latent heat energydelivered to the user's body stimulates circulation and facilitatesdissipation of the heat energy to avoid harm. Alternatively, the designof the wrap may modify the contact time of the water-vapor with the skinsuch that the contact time is insufficient to condense all of the watervapor; hence reducing the energy transfer to the skin.

In an exemplary embodiment the water vapor is made safe for skin contactby regulating the mixture of water vapor and air to a water vapor to dryair ratio of less than about 0.085 lb water vapor/lb dry air. Byregulating the ratio of water vapor to air, the water vapor in the watervapor-air mixture will condense at a dew point temperature such thatheat can be optimally and safely transferred to a user's skin withoutthe risk of thermal injury. As used herein, “dry air” refers to air withno appreciable water content.

The descriptions herein include an exemplary embodiment using two pairsof water vapor-air mixing layers and two pairs of water vapor-airdistribution layers. However as one skilled in the art will appreciatethat one or a plurality of two, or more water vapor-air mixing layersand one or a plurality of, two, or more water vapor-air distributionlayers or some combination thereof may also be used in the practice ofthe invention. Adjustment of location, thickness, air permeability, andmoisture vapor transmission rate of each layer an/or type of materialmay be desirable to create a suitable thermal and air mixing environmentin embodiments having a plurality of mixing layers and/or distributionlayers.

In one exemplary embodiment, the ratio of water vapor to dry air can beregulated by utilizing one or more longitudinal strips, disposedparallel to a row of multiple heat cells. The strip(s) may function as aportion of the water vapor-air regulating portion. Referring to thesimplified schematic drawing in FIG. 2, in an exemplary embodiment,thermal heat cells 50 are aligned in rows on the body of a wrap 52. Afoam strip 54 overlays longitudinally each of the row of heat cells 50forming air channels 56. It is preferable that the strip 54 bepositioned in the moist heat system between the heat cells 50 and thelatent heat delivery surface in moist heat system. The longitudinalstrips can serve to create an air space parallel to a row of multipleheat cells. The air space can aid in providing even flow of air into thewater vapor generating portion, and aid in water vapor-air mixing. Theheight of the longitudinal strips can be adjusted such that the ratio ofwater vapor to dry air is less than 0.085 lb water/lb of dry air, andalternatively less than about 0.060 lb water/dry air. It is believedwithout wishing to be held to the theory that a strip over a pluralityof heat cells enables the plurality of heat cells covered by the stripto act and/or be impacted cooperatively. In is not necessary that allheat cells be grouped and/or aligned in rows and covered by a strip. Insome embodiments only one row or group or a portion of the rows orgroupings of heat cells may be covered with a strip.

Water Vapor-Air Mixing Layer

In one exemplary embodiment the at least one water vapor-air mixinglayer can comprise an aerated structure of between about 18 gsm andabout 430 gsm (grams per square meter), and alternatively about 50 gsmto about 150 gsm. The at least one water vapor-air mixing layer can havea caliper-measured thickness according to ASTM Method No. D5729 of fromabout 1 mm to about 19 mm, alternatively from about 0.1 mm to about 4mm, alternatively from about 0.1 mm to about 5 mm and alternatively fromabout 1 mm to about 4 mm.

Non-limiting examples of materials suitable for the water vapor-airmixing layer include woven materials; non-woven materials includingwet-laid, air-laid, point-bonded, needle-punched and thermally bondednon-woven materials; fabrics; polyethylene; polypropylene; polyester;wood pulp; rayon; fibrous plant-based materials including celluloses,wool, silk, jute, hemp, cotton, linen, sisal, ramie; and combinationsthereof.

The at least one water vapor-air mixing layer has an air permeability offrom about 400 cm³/cm²/sec to about 17,000 cm³/cm²/sec, andalternatively from about 1,000 cm³/cm²/sec to about 1,500 cm³/cm²/sec,as measured by ASTM Method No. D737, and a moisture vapor transmissionrate of from about 5,000 g/m²/24 H to about 7,000 g/m²/24 H, andalternatively from about 5,500 g/m²/24 H to about 6,500 g/m²/24 H, asmeasured by ASTM Method E96.

Water Vapor-Air Distribution Layer

In one exemplary embodiment, the at least one water vapor-airdistribution layer can comprise a layer of insulative material having acaliper-measured thickness, according to ASTM Method No. D5729, of fromabout 0.1 mm to about 13 mm, alternatively from about 0.5 mm to about 6mm, and alternatively from about 1 mm to about 2 mm. The at least onewater vapor-air distribution layer can have a basis weight of from about5 gsm to about 430 gsm, alternatively from about 5 gsm to about 50 gsm,and alternatively from about 5 gsm to about 25 gsm, as measured by ASTMMethod No. D3776. The material of the water vapor-air distribution layeris substantially air and moisture impermeable, and can be resistant tocompression.

Non-limiting examples of materials suitable for the water vapor-airdistribution layer include polyethylene-based foam, polypropylene-basedfoam, polyester-based foam, polystyrene-based foam, polyurethane-basedfoam, foamed plastic sheet, plastic film, foil, paper-foil laminate,paper, non-woven, sponge, glass wool, fiberglass, and combinationsthereof.

The air and moisture impermeable material can have an air permeabilityof less than about 0.025 cm³/cm²/sec, measured using ASTM Method No.D737, and a moisture vapor transmission rate of less than about 200g/m²/24 H as measured using ASTM Method No. E96. The material can alsohave a thermal conductivity of from about 0.5 W/m*K to about 285 W/m*K(K degrees Kelvin) and a density of from about 5 kg/m³ to about 150kg/m³. Thermal conductivity of this material can be obtained from thefollowing source: “For Computer Heat-Conduction Properties Data” A. L.Edwards, UCRL-505 Copyright K&K Associates 1997.

In some embodiments, it may be desirable to selectively perforate, theair and moisture impermeable material to form the water vapor-airdistribution layer and allow passage of air and water vapor through tothe user, and to allow air to enter and to reach the water vaporgenerating portion, particularly if an exothermic oxidation reaction isused as the mechanism for water vapor generation. Alternativelyapertures and/or channels may be employed to allow passage of air andair-water vapor mixtures.

While the materials used for the water vapor-air distribution layer maybe substantially impermeable to air and water vapor, they should beassembled, constructed or configured such that the overall airpermeability of the vapor-air distribution layer is from about 500cm³/cm²/sec to about 2500 cm³/cm²/sec, alternatively about 1000cm³/cm²/sec to about 2500 cm³/cm²/sec and alternatively about 1500cm³/cm²/sec to about 2300 cm³/cm²/sec as measured by ASTM Method D737.The moisture vapor transmission rate of the vapor-air distribution layeris from about 6,000 g/m²/24 H to about 9,000 g/m²/24 H, alternativelyfrom about 7,000 g/m²/24 H to about 8,500 g/m²/24 H, alternatively fromabout 7,500 g/m²/24 H to about 8,500 g/m²/24 H, and preferably about8,100 g/m²/24 H as measured by ASTM Method E96.

Longitudinal Strips

As described above for one embodiment, the water vapor-air regulatingportion can also comprise longitudinal strips. Longitudinal strips canbe used to provide additional air to the system for reaction and toprovide additional water vapor-air mixing. The longitudinal strips cancomprise any flexible and non-compressible material. The height of thelongitudinal strips can be adjusted to achieve a desired water vapor toair ratio of less than about 0.085 lb water/lb dry air, andalternatively less than about 0.060 lb water vapor/lb dry air.Non-limiting examples of materials suitable for use in the longitudinalstrips include polyethylene-based foam, polypropylene-based foam,polystyrene-based foam, polyurethane-based foam, foamed plastic sheet,plastic film, foil, paper-foil laminate, non-wovens, sponge, glass wool,fiberglass, and combinations thereof. The longitudinal strips can bedisposed proximate the latent heat delivery surface the system, whetherthe system is a single-use disposable system, or whether the system is areusable system. Optionally, for a re-usable system in which a portionof the system is disposable the longitudinal strips can be a portion ofeither the disposable or reusable portion.

Latent Heat Delivery Surface

The latent heat delivery surface is in communication with the watervapor-air regulating portion and abuts or is adjacent to a target usersurface when the system is in use. The latent heat delivery surface maycontact the user surface (e.g. the skin in the case of human use) oralternatively be positioned with a predetermined gap between the latentheat delivery surface and the user surface. The latent heat deliverysurface may be a surface on a portion of the water vapor-air regulatorportion or alternatively a separate layer. In an exemplary embodimentthe latent heat delivery surface may be, for example, a layer ofmaterial that has a basis weight of from about 20 gsm to about 100 gsm,alternatively from about 40 gsm to about 90 gsm and particularly fromabout 80 gsm to about 82 gsm. In an exemplary embodiment the latent heatdelivery surface may have, for example, a caliper-measured thickness offrom about 0.05 mm to about 12 mm, and alternatively from about 0.1 mmto about 5.0 mm, and alternatively from about 0.2 mm to about 2 mm. Thelatent heat surface can have an air permeability of from about 200cm³/cm²/sec to about 500 cm³/cm²/sec, alternatively from about 300cm³/cm²/sec to about 400 cm³/cm²/sec, and particularly about 314cm³/cm²/sec measured using ASTM Method No. D737. The latent heat surfacecan have a moisture vapor transmission rate of greater than about 5,000g/m²/24 H measured using ASTM Method No. E96.

Non-limiting examples of suitable materials for the latent heat deliverysurface include nylon, rayon, cellulose ester, polyvinyl derivatives,polyolefins, polyamides, polyesters, polypropylenes, celluloses, wool,silk, jute, hemp, cotton, linen, sisal, ramie, and combinations thereof.

Exterior Surface Layer the of System

It is preferable that the exterior surface layer of the system opposingthe latent heat delivery surface side (i.e. in a exemplary embodimentfor human use the outer side of the water vapor generating portion orsurface furtherest from the skin) can comprise an insulative layer thatprevents the non-skin facing side of the system from becoming too hot,and that also directs heat downward toward the skin-facing side of thesystem. The insulative layer can be placed adjacent the opposed side ofthe heat cells or other water vapor source forming the water vaporgenerating portion.

Non-limiting examples of materials suitable for an insulative layerinclude polyethylene-based foam, polypropylene-based foam,polystyrene-based foam, polyester-based foam, polyurethane-based foam,foamed plastic sheet, plastic film, foil, paper-foil laminate,non-wovens, sponge, glass wool, fiberglass, and combinations thereof.

Such an insulative layer can have a caliper-measured thickness,according to ASTM Method No. D5729, of from about 0.1 mm to about 3 mm,alternatively from about 0.5 mm to about 2.5 mm, alternatively fromabout 1 mm to about 2 mm, and alternatively of about 1 mm.

Such an insulative layer has an air permeability of less than about0.025 cm³/cm²/sec measured using ASTM Method No. D737, and a moisturevapor transmission rate of less than about 250 g/m²/24 H measured usingASTM Method No. E96. The insulative layer also has a thermalconductivity of from about 0.5 W/m*K to about 285 W/m*K (K degreesKelvin) and a density of from about 5 kg/m³ to about 150 kg/m³. Thermalconductivity of this material can be obtained from the following source:“For Computer Heat-Conduction Properties Data” A. L. Edwards, UCRL-505Copyright K&K Associates 1997.

An optional one or more outermost layer of material can be addedadjacent the insulative layer. Non-limiting examples of such anoutermost material include those described above for skin contactlayers. The insulative layer and outermost material can also be formedas a pre-combined laminate. Optionally, this outer most layer ofmaterial may act as a covering and/or be a part of the structure forholding the device in place in use.

The various layers of the heat generating and/or water vapor-airregulating portion and/or latent heat delivery surface can be bondedtogether in any number of ways known to those of skill in the art.Non-limiting examples of suitable attachment methods include heatsealing around the periphery of the layers; hot melt glue or adhesivebetween each layer; spray-on adhesive; ultrasonic bonding/welding;pressure bonding; crimping and combinations thereof. In some embodimentsit may be desirable to selectively bond only some of the layers.

Moldable Portion

Optionally, the system of the present invention can also comprise amoldable portion and or be positioned in a molded structure. Themoldable portion can provide additional flexibility and stability foruse of the system on portions of the body on which it may be difficultto achieve a good fit, such as the face and/or head.

Non-limiting examples of materials from which the moldable portion canbe formed include metal foil, metal wire frame structure, flexibleplastic structure, flexible laminate structure, and combinationsthereof. Such a moldable portion can be incorporated within thestructure of the system, or can be an external structure removably ornon-removably attachable to an outer surface.

Heat Wraps

The wraps, packs or patches comprising moist heat systems may beself-contained or alternatively placed in a holder. A self containedembodiment may be directly attached to the user such as, for example, byan adhesive or by material extensions that form a wrap that can besecured by lapping, tying or fasteners. It should also be understoodthat the device may be a single use device or reusable or partiallyreusable. For reusable devices, replaceable parts such, as for example,the heat source should be conveniently removable, but securable intoposition for use.

Suitable materials for holders include, but are not limited to,materials listed as suitable for use for the latent heat deliverysurface and/or exterior surface layer.

Method of Manufacture

Extothermic Composition Heat Cells

The particulate exothermic compositions of the present invention can beprepared by any known or otherwise effective technique suitable forproviding an exothermic composition that provides a moist therapeuticheat benefit. The particulate exothermic compositions of the presentinvention are preferably prepared using conventional blending techniquessuch as the blending technique described herein. Other suitable methodsof blending the components of the particulate exothermic compositions ofthe present invention are more fully described in U.S. Pat. No.4,649,895 to Yasuki et al., issued. Mar. 17, 1987.

In a preferred embodiment, a particular technique of blending thecomponents of the particulate exothermic compositions involves addingcarbon to a blender or mixer, followed by adding a small amount of thetotal water, and then mixing the carbon/water combination. Usuallyenough water is added to assist in blending while avoiding prematureexothermic reaction. Mixing is stopped and an absorbent gelling materialis added to the carbon/water combination. Mixing is resumed until allthe components are mixed thoroughly, and then iron powder is added andmixed. The composition is then blended until thoroughly mixed to form aparticulate pre-mix. Sodium chloride, optionally a hydrogen gasinhibitor such as sodium thiosulfate, and the remaining water areseparately mixed to form a brine solution which is then added to theiron powder pre-mix to form a particulate exothermic composition that isuseful in the construction of a heat cell of the present invention.

In an exemplary embodiment, heat cells, having two opposed surfaces canbe prepared by adding a fixed amount of the particulate pre-mixcomposition to a pocket in a film layer substrate sheet such as a pocketin a polypropylene/poly(ethylene-vinyl acetate)(EVA) coextruded filmlayer substrate sheet. In this process, water or brine is rapidly dosedon top of the pre-mix composition, and an aerated structure such as astructure formed of a polypropylene SMMS non-woven substrate is placedover the cell, as a surface opposing and facing the EVA film side of thepreformed pocket-containing sheet. The film layer and non-woven layerare bonded together using a low heat, forming a unified structure. Theresulting heat cell contains the particulate exothermic compositionsealed in the pocket between the film layer and aerated structure.

It has been found that heat cells prepared by the method describedherein are especially effective in providing high water vapor generationinitially and throughout the desired heat treatment, provided that theheat cells comprise an exothermic composition comprising a select medianparticle size ratio of absorbent gelling material to iron powder definedherein.

Alternatively, individual heat cells can be prepared by using vacuum toform a pocket. That is, vacuum is used to draw the film layer substratesurface into a mold as the particulate premix composition is placed ontop of the film layer substrate surface directly over the mold. Theparticulate pre-mix composition drops into the vacuum formed pocketwhich is held in place by the vacuum exerted upon the film in the bottomof the mold. Next, a brine solution is rapidly dosed on top of thepre-mix composition. An aerated structure such as an SMMS polypropylenenon-woven substrate surface is then placed over the first film layersubstrate surface to form a surface opposing the first film layersubstrate surface, such that the particulate exothermic composition iscontained between the two opposed surfaces. The particulate exothermiccomposition is then sealed between the first and second opposedsurfaces. Once the heat cells are formed and sealed, the vacuum isreleased. This particular structure and method of making a plurality ofheat cells is particularly advantageous for a moist heat wrap because iteliminates a need to have a separate moisture-impermeable film to keepthe generated water vapor directed toward the skin-facing side of thedevice.

The resultant heat cells can be used individually or as a plurality ofheat cells. A plurality of cells is typically desirable for atherapeutic heat treatment. The use of a single heat cell may be usefulfor a drug delivery application, for example. The heat cells can beincorporated into various portable devices such as disposable and/orreusable body wraps, multi-purpose wraps, bandages, blankets and thelike. Some body wraps that can include the moist heat delivery systemssuch as for example, back wraps, knee wraps, neck wraps, menstrualwraps, joint wraps, hand/wrist wraps, neck-to-arm wraps, facial wraps,foot wraps, body wraps, blankets, bandages, patches, packs,multi-purpose wraps, and combinations thereof can have a means forretaining the wraps in place around/against various parts of the body,The retaining means can include, but are not limited to, adhesivesand/or fastening system such as a re-closable two-part hook and loopfastening system, ties, fasteners and the like.

Alternatively, the water vapor generating portion, for example formed ofa plurality of heat cells, can be disposable, and fittable into are-usable device such that a portion of the device is disposable and aportion reusable. By way of non-limiting example, the water vaporgenerating portion can be disposable and the water vapor-air regulatingportion can be reusable.

The resultant heat cells are packaged within 1 to 5 minutes after dosingwith the brine solution in a secondary air-impermeable package toprevent the oxidation reaction from occurring until desired, asdescribed in the aforementioned U.S. Pat. No. 4,649,895. Heat cells canalso be packaged at a later time provided they are kept in anenvironment free from oxygen using means known to those skilled in theart such as nitrogen blanketing.

Additional layers can be added or layers can be modified on theskin-facing side of the device, the opposing side, or both as desiredfor various effects and performance. Examples include but are notlimited to, a non woven skin facing layer can be texturized to impartsoftness or a layer can be impregnated with an aroma or active.

By way of non-limiting example, as described below, one or moreinsulative layers can be added to either the skin-facing side or theopposing side. Alternatively or in addition, various other layers can beadded, as described below, to the skin-facing side of the device. Thefinal structure can be sealed around the perimeter through all of thelayers with a perimeter seal, or each layer can be sealed to adjacentlayers using sealing systems, non-limiting examples of which includespray-on adhesive, ultrasonic bonding, polymer welding systems, hot meltglue or adhesive between each layer, pressure bonding, crimping, andcombinations thereof.

In one exemplary embodiment the heat cells may have different heatingoutput. For example, there can be a combination of high moist heat/shorttime heat cells with lower moist heat/longer time heat cells. Examplesof ways in which the duration of heating of a heat cell may becontrolled include, but are not limited to, the amount of exothermicparticulate composition material included in the cell and/or the amountof moisture available for forming water vapor. Another exemplaryvariation is to use one or more moist heat delivery system thermal cellsin combination with one or more conventional conduction thermal cells ina single device.

The system of the present invention can optionally incorporate atherapeutic component to be delivered through the skin, wherein theoptional therapeutic component includes aromatic compounds, non-activearomatic compounds, cosmetic actives, pharmaceutical actives,moisturization actives, health actives, nutritional supplements,aromatherapy agents, other therapeutic agents, and combinations thereof.

The amounts of such actives can vary, depending on the particularactive. The amounts provided by embodiments of the present invention aregenerally less than those required for dosing through the skin in a dryenvironment, such as with a dry heat mechanism.

The optional therapeutic component can be incorporated into the watervapor generating portion as a separate substrate layer, incorporatedinto at least one of the substrate layers forming the heat cells,incorporated into the chemistry contained in the heat cells,incorporated into separate active-containing cells, or incorporated intoa separate, discrete device to be used with the water vapor generatingportion and water vapor-air regulating portion. The heat cells can alsocomprise a separate substrate layer, or be incorporated into at leastone of the opposing surfaces, a self-adhesive component and/or asweat-absorbing component.

The invention is amenable to a wide variety of types of active materialsincluding but not limited to, volatile materials, water solublematerials, materials with limited water solubility at ambienttemperature and combinations thereof. Further, in some cases waterinsoluble materials may be utilized in the system such as, for example,when presented to the system in combination with suitable solvents orsolubilizers.

Non-limiting examples of active aromatic compounds include aromatherapyagents, menthol, camphor, eucalyptus, and mixtures thereof. Non-limitingexamples of non-active aromatic compounds include benzaldehyde, citral,decanal, aldehyde, and combinations thereof. Non-limiting examples ofcosmetic actives include moisture-enhancing actives, wrinkle-reducingactives, skin-tone enhancing actives, skin lightening actives, skindarkening actives, and combinations thereof. Non-limiting examples ofpharmaceutical actives/therapeutic agents include antibiotics, vitamins,nutritional supplements, herbal agents, antiviral agents, analgesics,anti-inflammatory agents, antipruritics, antipyretics, anestheticagents, decongestants, mucolytics, antitussives, antihistamines,pain-relieving actives, antifungals, antimicrobials, and combinationsthereof. In particular, non-limiting examples of pain-relieving activesinclude aspirin, salsalate, diflunisal, ibuprofen, ketoprofen,nabumetone, piroxicam, naproxen, dicloenac, indomethacin, sulindac,tolmetin, etodolac, ketorolac, oxaproxin, celecoxib, and combinationsthereof.

The present invention has many uses, non-limiting examples of whichinclude delivering consistent, safe, efficient, and sustained moistheat, pain relief, deep muscle heating, increased blood flow, reducedcardiac work, wound healing, body warming, delivery of actives, deliveryof moisture, respiratory relief, skin hydration, enhanced sleep,physical therapy, and combinations thereof. The shape, size and form ofthe system may be varied to facilitate the particular selected use,i.e., body wrap, facial wrap, multi-purpose wrap, bandage, blanket, andthe like.

For human use the system safely and efficiently delivers a large amountof latent heat while maintaining a skin surface temperature of fromabout 36° C. to about 50° C., alternatively about 36° C. to about 45°C., alternatively about 36° C. to about 42° C., alternatively about 36°C. to about 43° C., alternatively from 38° C. to about 42° C., andalternatively from about 38° C. to about 40° C. The system also providesa skin surface temperature of about 36° C. within about 5 minutes ofinitiation of heating. In addition in one embodiment, the systemprovides a skin surface temperature of at least 38° C. for at leastabout 60 minutes as measured by thermocouple.

In one embodiment the system is able to deliver safe heat by adjustmentof the dew point temperature of the water vapor-air mixture delivered tothe skin surface. The dew point is adjusted by adjusting the proportionof water vapor to air or humidity ratio. In an exemplary embodiment, thewater vapor-air mixture has a humidity ratio of water vapor to air thatis less than 0.065 lb water vapor/lb dry air, and alternatively, lessthan about 0.060 lb water vapor/lb dry air, which corresponds to a dewpoint temperature of from about 40° C. to about 50° C.

Because the temperature of the water vapor-air mixture of the system inuse on a body is only a few degrees above normal skin temperature offrom about 32° C. to about 35° C., and the dew point temperature of thewater vapor-air mixture is approximately that of normal skin temperaturewhen it reaches the skin, heat can be safely transferred to the skin vialatent heat of condensation of water from the water vapor-air mixture.Thus, the system is able to safely deliver a large amount of heat to theskin, wherein from about 15% to about 95%, alternatively from about 20%to about 80% and alternatively from about 40% to about 75% of the heatis delivered as latent heat. In a one embodiment, the moist heat systemdelivers about 15% to about 95% of the heat as latent heat ofcondensation for at least 10 minutes, alternatively, at least 30 minutesor alternatively, for at least about 1 hour, alternatively, for at leastabout 3 hours, or alternatively, for at least about 5 hours.

In addition to delivering heat the moist heat system may also providemoisturization to tissues as the water vapor condenses to water anddelivers the latent heat of condensation to the tissue.

Skin surface temperature may be measured by the following method.Temperature measurements may be made using a thermocouple. Temperaturemeasurements may be made by positioning a thermocouple between the skinand the latent heat delivery surface. In an exemplary embodimenttemperature measurements are made with K-type thermocouples (Omega, part#5SRTC-TT-K-40-72) and recorded by temperature data logger (Omega,HH84). To measure the temperature of the surface of a user's skin, theuser sits in a room at about 22° C. for about 20 minutes to normalizethe skin to the room temperature and conditions. During that time, athermocouple is placed and taped on the skin surface, taking care thatthe tape is not placed over the sensing area of the thermocouple. Uponexpiration of the equilibration time, temperature can be measured andrecorded for a desired period of time.

To facilitate standardization of the test results in some embodiments isdesirable to construct the moist heat system to be measured, seal it inan impermeable container and set it aside for 24 hours to equilibratebefore testing. When a system is to be tested, it is removed from theimpermeable container/protective packaging to activate the heat cell andplaced on a user's body part, typically the forearm or back, with thetemperature measurement device, e.g. thermocouple and/or heat fluxsensor, touching the body part between the body part and the measurementdevice. A single measurement may be made or alternatively a series ofmeasurements over time. Typically, skin temperature may be measuredbefore application of the system to be tested and/or after applicationof the system for reference purposes. This may be accomplished byplacing the measurement device on the skin.

All measurements are preferably made at ambient environmentalconditions, i.e. a temperature range of about 21° C. to about 23° C. andrelative humidity range of about 38% to about 42% in the laboratory orarea in which the measurements are made.

The dew point temperature is preferably measured when the moist heatsystem is activated and in position on a user as the dew pointtemperature of particular interest is related to the amount of watervapor between the body and the moist heat wrap. The amount of watervapor between the body and the moist heat wrap is dependent on theamount of water vapor generated by the wrap minus the amount of watervapor condensed and the amount of water vapor that flows out of thewrap.

Dew point temperature may be measured with a Vaisala HUMICAP® HMT337 dewpoint transmitter (Vaisala) with Stainless Steel HM47453SP filter. Thisunit is manufactured by Vaisala and is obtained from their US office at10 D Gill St., Woburn, Mass. 01801 Tel 1-888-824-7252. This instrumenthas a heated humidity probe which prevents condensation on the probe inhigh humidity environment. To record the dew point temperature the moistheat wrap is activated to begin production of heat and water vapor andplaced on the surface of a user. For a human user the skin of the backor forearm is convenient but may be measured at any surface where thedevice may be used. It is preferable to allow 1-5 minutes for the systemto “stabilize” before beginning measurements. To make a measurement thehumidity probe is inserted between the moist heat pack and the usersurface and allowed to stabilize. The dew point temperature is displayedon the transmitter of the measurement device. The dew point temperaturemeasurement is taken after it has stabilized for about 90 seconds. Theprobe measures a very localized environment, thus it may be desirable tomake multiple measurements at various positions between the wrap and thesurface.

The system of the present invention as described herein can generate anddeliver from about 75 W/m² to about 500 W/m², alternatively from about100 W/m² to about 200 W/m², alternatively from about 200 W/m² to about500 W/m², and alternatively from about 300 W/m² to about 500 W/m² ofheat flux at a safe skin temperature.

Heat generated and/or transferred may optionally be monitored and/ormeasured using infrared imaging. An FLIR Systems SC660 Infrared Cameramanufactured by FLIR System equipped with FLIR ExaminIR Software forimage analysis and a MX 350 24″ Tabletop Tripod or similar.

The moist heat system generates and delivers heat to a surface of theskin wherein from about 15% to about 95%, alternatively from about 20%to about 80%, and about 40% to about 75% of the heat delivered to asurface of the skin is delivered as latent heat upon condensation of thewater vapor-air mixture. Without wishing to be held to the theory, it isbelieved that the remainder of the heat transferred to the user is heattransferred by conduction. Because a majority of the heat transfer isthrough condensation on/in the body through control of the dew pointtemperature by water vapor-air mixing, the system of the presentinvention can deliver peak heating levels to the body of up to two tofive times that of a conventional dry heating wrap while maintainingconstant skin temperature of about 43° C. or less, thereby providing asafe usage experience for the user.

The system produces heat at different rates during the reaction.Initially the system produces water vapor at a very high rateapproaching 2.0 mg/min/cm² of water vapor generation. During this periodthe rate of heat transfer to the skin is very high as the latent heat ofcondensation of this amount of water vapor over about the first 30minutes of system use causes a large increase in heat flux to the skin,thereby increasing deep muscle and skin temperature very rapidly. Thatthe heat is delivered by latent heat of condensation is demonstrated bystable skin temperature that occurs within about 10-60 minutes ofapplying the system and then stabilizes at an equilibrium dew pointtemperature between the water vapor and the condensing water vapor atthe skin surface. The continued addition of high heat flux to the skinat the constant temperature demonstrates that latent heat is responsiblefor at least about 15% and up to about 95% of the heat transfer to thedeep muscle tissue, while maintaining a constant selected temperaturewhich is less than the temperature that would cause harm or damage tothe skin. In an exemplary embodiment for human use a temperature of lessthan about 43° C., alternatively less than about 41° C., oralternatively less than about 39 C.°.

The increased moisture content of the skin also improves the thermalconductivity of the skin and improves the rate of heat transfer throughthe skin and deeper into the underlying tissue. Once the initial watervapor generation rate has raised the deep tissue and skin temperature toa therapeutic level the water vapor generating portion is designed suchthat water vapor generation rates are reduced to a lower level ofbetween about 0.05 mg/min/cm² and about 1.0 mg/min/cm². At this lowersustained rate the system continues to produce water vapor that providesenough latent heat to maintain the skin and deep tissue temperature atthe desired therapeutic temperature achieved within the first 10-30minutes of system use for the duration of the system use.

Latent heat can deliver the heat benefit of the system to a user becauseof the large amount of heat flux, e.g. the ability to supply sufficientheat to raise the temperature of body tissue mass to a therapeutictemperature within 10-30 minutes of initiation of heating of the systemwithout exposing the skin to a damaging temperature; i.e. maintaining askin temperature of less than about 43° C. This is in contrast toconventional dry heat wraps that rely on conductive heat transfer wouldrequire that the skin temperature be raised to above 50° C. to deliver adeep muscle temperature of 38° C. in less than one hour.

In one exemplary embodiment the energy output of a moist heat deliverysystem of the invention is about 75 W/m² to about 500 W/m² heat fluxalternatively from about 100 W/m² to about 300 W/m² heat flux andalternatively from about 150 W/m² to about 250 W/m² as compared to aconventional dry wrap which typically delivers from about 50 W/m² toabout 100 W/m² of heat flux. This is a difference in heat delivered tothe body of about 3 times over the same period of time at a safeapplication temperature.

Heat flux can be measured by using a PU_22 (Huksaflux, HuksefluxUSA,Inc. P.O. Box 850, Manorville, N.Y. 11949, heat flux sensor. Signalsfrom the heat flux sensor are read with an OM-DAQPRO-5300 logger (OmegaEngineering Inc., address: One Omega DR., Box 4047 Stamford, Conn., USA,phone (203)359-1660). The unit is programmed to convert the millivoltsignals it receives from the heat flux sensor to W/m². A USB interfaceis used to transfer data form the logger to a computer. In an exemplarymeasurement, the data is recorded for 1 hour at 10 second interval. Inmaking a measurement, the heat flux sensor(s) is first connected to thelogger and data recoding is initiated in the software. The moist heatsystem to be tested is removed from its sealed storage pouch orcontainer and activated by contact with air. The moist heat system isplaced with the side that is releasing water vapor on top of the heatflux sensor. Once the heating device is placed on the heat flux sensor,acquisition of data begins and measurements are then recorded for thedesired period of time. The heat flux results are tabulated and can beplotted against time. Such a plot is particularly useful to help definethe time intervals representing the maximum heat flux, the steady stateheat flux and the interval with decreasing heat flux.

Measurement of Latent Heat

Latent heat released can be determined using the heat flux and waterloss/generation rate. For determining the % of total heat of a moistheat system that is latent, the thermal output (e.g. heat flux) of themoist heat wrap is measured when the system is placed with its permeableside facing up. This is done in order to allow the moisture to freelyescape from the wrap and not be re-absorbed back to the wrap. To measurethe total heat flux the moist heat wrap is placed on top of a heat fluxsensor that is attached to the surface of a constant temperature platemaintained at 36° C. in an environment at a temperature of 23° C. and arelative humidity of 40%. The temperature plate is maintained at aconstant temperature by circulating water from a temperature controlledcirculating water bath available from VWR Scientific, Suwanee, Ga., USA,model 1157, at a rate of 1.3 L/min. A constant temperature plate thatcan be used is described in JIS S 4100 (Japanese Standards Association).

The water vapor generation rate is determined by measuring the weightchange of the moist heat system. The method for determining the watervapor generation rate is described below. To calculate latent heat thewater loss rate is multiplied by the latent heat of water which is 2.261kJ/gm of water.

The heat flux and water loss rate are plotted. Calculation of the %total heat flux that is due to latent heat can be performed by examininggraphs of the heat flux and water vaporization rate to determine thetime intervals of each that have the maximum heat flux and the longeststeady state behavior. Multiple time points may used to calculate arange of heat flux provided because in one embodiment both rapid heatingand water vapor generation as well as sustained heating and water vaporgeneration are provided. Thus, heat flux and water vapor generation canvary over the course of the exothermic reaction.

For one exemplary 24 cell moist heat wrap in which heat was measured atfive regularly spaced intervals over a 60 minute time period, thepercentage of total heat that was latent heat ranged from about 42% toabout 61%. More specifically, the percentage of total heat that waslatent heat was 49%, 61%, 61%, 42% and 47% for measurements one to five,respectively. The total amount of heat was about 750 W*min/m², about2400 W*min/m², about 5000 W*min/m², about 3400 W*min/m², and about 1500W*min/m² for measurements one to five, respectively. This example isprovided solely for the purpose of illustration and should not beconstrued to be a limitation as many other variations of the presentinvention are possible.

The heat flux and water vapor loss rate are used to calculate the % heatflux due to latent heat at each time interval. The equation used isshown below:

${\%\mspace{14mu}{heat}\mspace{14mu}{from}\mspace{14mu}{latent}\mspace{14mu}{heat}} = {100 \times \frac{{Water}\mspace{14mu}{vapor}\mspace{14mu}{loss}\mspace{14mu}{rate}\mspace{14mu}( {{gm}\text{/}m^{2}\min} ) \times 2.261\mspace{14mu}{kJ}\text{/}{gm}\mspace{14mu}{water}}{{Heat}\mspace{14mu}{flux}\mspace{14mu}( {{kJ}\text{/}m^{2}\min} )}}$  1  W = 1  J/s.

The systems and methods of the present invention transfer to the userfrom about 15% to about 95%, alternatively from about 20% to about 80%and alternatively from about 40% to about 75% of the heat generated aslatent heat.

The production and quantity of latent heat transferred by the moist heatsystem is distinguishable from prior devices marketed as “steam” heatdevices which typically when tested by this method show no detectableamounts of latent heat transfer.

The portable moist heat delivery system of the present invention, whenapplied to the body, also dramatically impacts skin and muscletemperature causing an increase in blood circulation/flow rates in thearea where the system is applied. Total cardiovascular work in the bodyis decreased due to application of the system even though localizedblood flow is dramatically increased.

An increase of from about 3 to about 9 times the resting blood flow rateof an area of skin prior to application of the system, during a timeperiod the system is applied to the area of skin of a user, is providedby the system. In an exemplary 24 moist heat cell embodiment, the systemincreased blood flow about 5 times versus a dry heat wrap, and anexemplary 12 moist heat cell embodiment, the system increased blood flowabout 2 times versus a dry heat wrap. Use of an exemplary 24 cell moistheat embodiment of the system for an hour increased the blood flowcomparably to a conventional hydrocollator treatment and more than aconventional Whirlpool treatment. This example is provided solely forthe purpose of illustration and should not be construed to be alimitation as many other variations of the present invention arepossible.

When cardiac workload is measured as a product of mean blood pressureand mean heart rate over a period of time, cardiac workload is decreasedby at least about 4% with application of the portable heat deliverysystem of the present invention to the skin of a human user. Cardiacwork is held essentially constant with the application of dry heat wrapsor other typical modalities of heating such as hydrocollators. In thecase of a whirlpool bath, the cardiac workload increased significantly,by over 20%, during a 15 minute application. The type of cardiacrelaxation provided by the present invention was previously unattainablewith portable moist heat devices.

Moist heat delivery systems may increase the deep muscle temperature toa temperature well above the typical resting temperature of about 36° C.at 2.5 cm below the skin surface to a temperature of about 38° C. Thesystem also provides a tissue temperature of at least about 38° C. at adepth of at least about 2.5 cm below an outer surface of the skin of auser within about 60 minutes from initiation of heating, whilemaintaining a temperature of the outer surface of the skin of less thanabout 43° C.

Furthermore, the system provides an increase in temperature of tissue atleast about 2.5 cm below an outer surface of the skin of a user of atleast about 1° C. above an initial tissue temperature measurement withinabout 20 minutes from initiation of heating, while maintaining atemperature of the outer surface of the skin of less than about 43° C.;of at least about 2° C. above an initial tissue temperature measurementwithin about 40 minutes from initiation of heating, while maintaining atemperature of the outer surface of the skin of less than about 43° C.;and of at least about 3° C. above an initial tissue temperaturemeasurement within about 60 minutes from initiation of heating, whilemaintaining a temperature of the outer surface of the skin of less thanabout 43° C.

Deep muscle temperature and skin temperature of a user during use ofexemplary 12 heat cell and 24 heat cell embodiments of the moist heatingsystem of the present invention were compared to deep muscle and skintemperatures for a conventional dry thermal heat cell device. Theexemplary 24 cell moist heat cell device, heated deep muscle to about38° C. with a maximum skin temperature of about 40° C. The exemplary 12cell moist heat cell device heated deep muscle to about 37.5° C. with amaximum skin temperature of about 40° C. The conventional dry heat celldevice heated deep muscle to less than about 36.5° C. after 60 minutesof heating with a maximum skin temperature of about 35° C. This exampleis provided solely for the purpose of illustration and should not beconstrued to be a limitation as many other variations of the presentinvention are possible.

Such a deep tissue temperature is typical of the type of thermal heatingpreviously only achievable with the use of whirlpool baths. The type ofheating capability provided by the present invention was previouslyunattainable with portable, moist heat devices.

Skin temperature and deep tissue temperature can be measured by thefollowing methods.

Skin temperature is measured with a thermistor probe, TSD202A producedby BIOPAC, Inc., Goleta, Calif. Such a probe is a “fast response” probewith a response time of 0.6 seconds and is 1.7 mm in diameter. Output ofthe probe is digitized with an MP100 16 bit ND converter, and stored ona computer.

Deep muscle temperature is measured with a T thermocouple probe andwire, part No. IT-18 produced by Physitemp Instruments, Inc., Clifton,N.J. USA. The thermocouple is 24 gauge with a time constant of 0.3seconds. The thermocouple is inserted into the tissue in a 22 gaugeneedle.

Prior to measuring deep muscle temperature, a subject is seated for 20minutes in a 22° C. room. During the 20 minutes, the thermistor andthermocouple are placed on and under the skin, respectively. The area ofthe subject where the thermistor and thermocouple are located is scannedwith a laser Doppler imager to measure skin blood flow. A heating deviceor modality to be tested (for example, conventional dry heat wrap, asystem of the present invention, a whirlpool, a hydrocollator, etc.) isapplied for a period of time that matches standard clinical therapyprotocols for the heating modality used. After the test period thetested area of the subject is scanned again to measure skin blood flow.After the end of the test period, the thermistor and thermocouple areremoved and the area where the thermocouple is placed is inspected andcleaned. Every 5 minutes during an experiment, the subject is asked tocircle, on a 10-point visual analogue scale, the subject's perception ofthe heat and degree of satisfaction with the heating modality.

The thermocouple is placed into the quadriceps tissue 2.5 cm from thesurface of the skin using a needle to penetrate the skin. To place thethermocouple into the tissue, a needle is inserted at a 60 degree angleto the skin, with depth verified by ultrasound imaging. Once thethermocouple is inserted, the needle is removed and the sterilethermocouple is left in place in the tissue. The limb of the subjectdoes not move during the test period to minimize any potential trauma tothe limb. To ensure sterility the thermocouple assembly is sterilizedwith CIDEX for one hour prior to use, and then washed in sterile saline.

The thermocouple is placed into the deep muscle tissue, and not the fatlayer. Placement is confirmed by ultrasonic measurement (Sonosite 180,Seattle Wash. USA) of the subject's upper thigh.

The output of the thermocouple is transduced by an Iso-thermex digitalthermometer system certified for human and hospital use. Such a deviceis accurate to 0.1% and is produced by Columbus Instruments, Columbus,Ohio, USA.

The thermocouple is left in place throughout testing and for 15 minutesafter removal of the heating modality. A system of the present inventionis left in place for 1 hour.

Skin blood flow can be measured using an infrared laser Doppler flowmeter, (TST 140 probe from Biopac systems, Goleta, Calif., USA). Thedevice has a 3 g flat probe with an active surface area of 1 square cm.The probe is plugged into a LDF 100C amplifier and digitized to 2,000samples per second with a 16 bit analog to digital converter (BiopacSystems, NP150, Goleta, Calif., USA). The unit is warmed for 30 minutesprior to flow measurements. The flow probe is calibrated prior to and atthe end of an experiment. The tissue volume sampled by the probe is 1mm³. A test subject sits in a 22° C. room for 20 minutes prior to anexperiment, during which time blood flow is measured.

Measurements are taken prior to applying a heating modality, immediatelyafter removing a heating modality, and at 5, 10 and 15 minutes afterremoving a heating modality.

Skin and muscle temperature over time, and skin blood flow can then beanalyzed.

Cardiac work is a calculated representation of the cardiac effort beingexpended by the body under certain conditions. Cardiac Work is definedas a product of the heart rate and a mathematical average of thediastolic and systolic blood pressure.Starting Cardiac work=the average starting heart rate×starting averageblood pressure.Starting average blood pressure=((average starting systolic bloodpressure−average starting diastolic blood pressure)×0.33+averagestarting diastolic blood pressure)/100.Finishing Cardiac work=the average finishing heart rate×finishingaverage blood pressure.Finishing average Blood pressure=((average finishing systolic bloodpressure−average finishing diastolic blood pressure)*0.33+averagefinishing diastolic blood pressure)/100.Difference in cardiac workload=Starting Cardiac workload−FinishingCardiac workload.

Heart rate is measured in beats per minute. Heart rate is measured by anindividual feeling a test subject's radial pulse over a period of oneminute.

Blood pressure is measured by auscultation of the right arm of a testsubject with an air sphygmomanometer. Systolic and diastolic pressuresare determined according to the procedure and standards of the AmericanHeart Association and provided in mmHg, with systolic being the firsttapping and diastolic being a change from a tap to a muffle. The bloodpressure cuff is inflated to 200 mmHg and the pressure reduced at 3 mmHgintervals per second.

The system can also provide perception of comfort and pain relief withinabout 10 minutes of initiation of heating of the system. To determinecomfort level and pain relief, a 0-10 point visual analog scale is usedto measure subjective comfort. Such a scale can be used, for example,during deep muscle testing described above in a test subject's leg.Comfort and pain relief is measured before a heating modality isapplied, and every 5 minutes during a first hour, then can be measuredeach hour thereafter for longer experiments. After a heating modality isremoved, comfort and pain relief is measured at 5, 10, and 15 minutes.Alternatively pain relief may be assessed by evaluating range of motionbefore and after treatment with the moist heat system.

The system of the present invention also generates from about 0.05 mgwater vapor/min/cm² to about 2.5 mg water vapor/min/cm² of water vaporgenerating portion, and alternatively from about 0.1 mg watervapor/min/cm² to about 2.0 mg water vapor/min/cm² of water vaporgenerating portion, wherein the water vapor delivers moisture to thesurface of the skin via condensation onto the surface of the skin.

The amount of water vapor generated, and water vapor generation rate canbe measured by measuring the weight change of a system of the presentinvention, or other exothermic heating device, from before initiation ofheating to after the system is spent, and over time during use of thesystem. To measure and record the weight change, a Mettler-ToledoBalance Model PG503-S is connected to a computer running ToledoBalanceLink (Mettler Toledo AG, CH-8606 Greaifensee, phone +41 44 944 2211) software using a RS232C interface cable. Prior to testing thebalance is calibrated according to the manufacturer's instructions. A 4inch thick stero-foam sheet is placed on top of the scale of the balanceand the balance is zeroed.

The system to be tested is removed from an air-tight foil pouch where itis stored after manufacture, is placed in the center of the stero foamsheet with the latent heat delivery surface facing up so that watervapor may escape, and data recording initiated.

The starting weight of the exothermic heating device and the weight ofthe exothermic heating device thereafter are recorded until the systemis spent, and thereby moisture loss from the start to the end of thereaction can be measured.

The amount of weight loss is correlated to the amount of water loss,which estimates the amount of water vapor generated during the reaction.With an exothermic composition such as that of the present invention,because none of the other components of the exothermic composition islost during the reaction, and water is not consumed as part of thereaction, weight lost can be correlated to water lost and water vaporgenerated. Measurements based on weight lost, and calculations of watervapor generated are approximations because during the course of thereaction iron oxide is produced, and thus some weight is also gainedduring the course of the reaction. However, a minimal amount of ironoxide is produced and thus a de minimus amount of weight is gained.Thus, the amount of weight lost approximates the amount of water lost.

Amount of water vapor generated per area of skin of a user can becalculated by dividing the total amount of water vapor generated by thesystem by the area of skin to which a system is applied. Water vaporgenerated per unit time can also be calculated by dividing the amount ofwater vapor generated by a system by the duration of water vaporgeneration. One of ordinary skill in the art would understand how toperform such calculations, either manually or using computer software.

In addition, the system can increase skin moisture level by at leastabout 300% versus skin moisture level prior to application of thesystem, over a time period of less than about 30 minutes.

Amount of skin moisture and increase in skin moisture is measured with aCorneometer 810 capacitance skin moisture meter (Courage KhazakaElectronics, Cologne, Del.). The corneometer determines the humiditylevel of the stratum corneum of the skin by electrical capacitance.Alteration in skin hydration level results in a change in capacitance.The capacitance probe is applied to the skin for one second at apressure of 7.1N/cm². The degree of skin capacitance is indicated from1-100 units. One unit represents a water content of the stratum corneumof 0.02 mg/cm² at a measuring depth of 20 nm. Very dry skin is less than30 units, dry skin is 30-45 units and sufficiently moisturized skin isgreater than 45 units.

Tissue (i.e. skin in this case) capacitance is measured by applyingelectromagnetic waves at a frequency of 100,000 cycles/second (Hz), to adepth of 20 nm, to image the skin surface. The probe is placed on theskin of a test subject at a location desired to be studied. Prior totesting, the subject sits in a room at about 22° C. and 40% relativehumidity for 20 minutes, to allow the skin to come to a normalizedcondition. Capacitance, from which skin moisture is calculated, ismeasured before and immediately after removal of the heating modality.

Methods of Use

A thermal device may be solely a moist heat system or a moist heatsystem used in conjunction with conventional conduction heating system.For example, a thermal device may comprise at least one moist heat celland at least one dry heat cell may be incorporated in a thermal device.This configuration may be useful, for example, in providing heat andmoist heat in a regulated manner to facilitate delivery of an aromaticsubstance or a therapeutic agent.

The present invention can provide methods of delivering consistent,safe, efficient, and sustained heat in a portable form to provide: painrelief, deep muscle heating, increased blood flow, reduced cardiac work,relaxation, wound healing, delivery of moisture, delivery of actives,body warming, respiratory relief, skin hydration, enhanced sleep,physical therapy, and combinations thereof depending on the shape, sizeand form of the system—i.e. body wrap, facial wrap, bandage, blanket,and the like.

An embodiment of the present invention includes a method of providingdeep tissue heating comprising:

-   -   (a) providing a portable moist heat system comprising a water        vapor generating portion comprising a water vapor source and a        heat source; and a water vapor-air regulating portion, said        water vapor-air regulating portion comprising a water vapor-air        mixing layer, and a water vapor-air distribution layer; said        water vapor generating portion and said water vapor-air        regulating portion being in fluid communication; and said water        vapor-air regulating portion having a latent heat delivery        surface disposed adjacent the water vapor-air regulating        portion;    -   (b) applying the system to the skin of a user;    -   (c) supplying a water vapor-air mixture generated by the system        to the skin of the user; and    -   (d) transferring heat to the skin of the user, wherein the        system transfers heat to the skin of a user and wherein from        about 15% to about 95% of heat to a user as latent heat of        condensation while maintaining skin temperature less than about        43° C.

The method can provide from about 75 W/m² to about 500 W/m²,alternatively from about 100 W/m² to about 200 W/m², alternatively fromabout 200 W/m² to about 500 W/m², and alternatively from about 300 W/m²to about 500 W/m² of heat flux.

In addition, the method can comprise the step of providing a skinsurface temperature of at least about 36° C. within about 5 minutes ofinitiation of heating of the system. The method also can provide atissue temperature of at least about 38° C., at a depth of at leastabout 2.5 cm below an outer surface of the skin, within about 60 minutesfrom initiation of heating of the system, while maintaining atemperature of the outer surface of the skin of less than about 43° C.

An embodiment of the present invention also includes a method ofproviding rapid pain relief comprising:

-   -   (a) providing a portable moist heat system comprising a water        vapor generating portion comprising a water vapor source and a        heat source; and a water vapor-air regulating portion, said        water vapor-air regulating portion comprising a water vapor-air        mixing layer, and a water vapor-air distribution layer; said        water vapor generating portion and said water vapor-air        regulating portion being in fluid communication; and said water        vapor-air regulating portion having a latent heat delivery        surface disposed adjacent said water vapor-air regulating        portion;    -   (b) applying the system to the skin of a user;    -   (c) initiating heating of the system; and    -   (d) supplying a water vapor-air mixture generated by the system        to the skin of the user; wherein the system provides pain relief        within about 60 minutes from initiation of heating of the system        while maintaining skin temperature less than about 43° C.

The method can further comprise the steps of providing a pain-relievingactive; and delivering the active through the skin. A pain relievingactive can be incorporated into the water vapor generating portion, intothe water vapor source, or into the water vapor-air regulating portion.A pain relieving active can also be incorporated into a separate devicethat is used in conjunction with the system of the present invention todeliver the pain relieving active through the skin.

An embodiment of the present invention also includes a method ofincreasing blood flow comprising:

-   -   (a) providing a portable moist heat system comprising a water        vapor generating portion comprising a water vapor source and a        heat source; and a water vapor-air regulating portion, said        water vapor-air regulating portion comprising a water vapor-air        mixing layer, and a water vapor-air distribution layer; said        water vapor generating portion and said water vapor-air        regulating portion being in fluid communication; and said water        vapor-air regulating portion having a latent heat delivery        surface disposed adjacent said water vapor-air regulating        portion;    -   (b) applying the system to the skin of a user;    -   (c) initiating heating of the system; and    -   (d) increasing blood flow, in an area of the skin of the user        where the system is applied, of from about 2 to about 9 times        versus blood flow of the area of skin prior to application of        the system, during a time period the system is applied to the        skin of a user; while maintaining skin temperature less than        about 43° C.

The present invention also includes a method of providing reducedcardiac work, and relaxation, comprising:

-   -   (a) providing a portable moist heat system comprising a water        vapor generating portion comprising a water vapor source and a        heat source; and a water vapor-air regulating portion, said        water vapor-air regulating portion comprising a water vapor-air        mixing layer, and a water vapor-air distribution layer; said        water vapor generating portion and said water vapor-air        regulating portion being in fluid communication; and said water        vapor-air regulating portion having a latent heat delivery        surface disposed adjacent said water vapor-air regulating        portion;    -   (b) applying the system to the skin of a user;    -   (c) initiating heating of the system; and    -   (d) reducing cardiac work by at least about 4% during a time        period the system is applied to the skin of a user while        maintaining skin temperature less than about 43° C. The time        period the system is applied to the skin of a user can be at        least about 1 hour.

An embodiment of the present invention also comprises a method ofproviding moisture to the skin comprising:

-   -   (a) providing a portable moist heat system comprising a water        vapor generating portion comprising a water vapor source and a        heat source; and a water vapor-air regulating portion, said        water vapor-air regulating portion comprising a water vapor-air        mixing layer, and a water vapor-air distribution layer; said        water vapor generating portion and said water vapor-air        regulating portion being in fluid communication; and said water        vapor-air regulating portion having a latent heat delivery        surface disposed adjacent said water vapor-air regulating        portion;    -   (b) applying the system to the skin of a user; initiating        heating of the system;    -   (c) generating from about 0.05 mg water vapor/min/cm² of water        vapor generating portion to about 10 mg water vapor/min/cm² of        water vapor generating portion, wherein the water vapor delivers        moisture to the surface of the skin via condensation onto the        surface of the skin.

The method can further comprise the step of increasing skin moisturelevel by at least about 300% versus skin moisture level prior toapplication of the system, over a time period of less than about 60minutes. The method can also comprise the steps of providing a cosmeticactive; and delivering the cosmetic active to the skin.

An embodiment of the present invention also includes a method ofproviding a benefit to a user comprising:

-   -   (a) providing a portable moist heat system comprising a water        vapor generating portion comprising a water vapor source and a        heat source; and a water vapor-air regulating portion, said        water vapor-air regulating portion comprising a water vapor-air        mixing layer, and a water vapor-air distribution layer; said        water vapor generating portion and said water vapor-air        regulating portion being in fluid communication; and said water        vapor-air regulating portion having a latent heat delivery        surface disposed adjacent said water vapor-air regulating        portion;    -   (b) applying said system to a surface of a user wherein the        latent heat delivery surface is located proximate the surface of        the user.    -   (c) initiating heating of said system; and    -   (d) transferring moist heat to the skin of the user at a        preselected temperature range, wherein the moist heat is about        15% to about 95% latent heat of condensation.

The method can further comprise further comprising the step of providinga benefit selected from the group consisting of reducing cardiac work byat least about 4% during a time period said system is applied to theskin of a user; increasing blood flow, in an area of the skin of saiduser where said system is applied, of from about 3 to about 9 timesversus blood flow of said area of skin prior to application of saidsystem; providing relaxation; providing wound healing; providingrespiratory relief; providing body warming; providing skin hydrationproviding enhanced sleep; providing physical therapy, promoting orenhancing post-operative recovery, promoting or enhancing injuryrecovery and combinations thereof.

EXAMPLES

The following examples further describe and demonstrate embodimentswithin the scope of the present invention. The examples are given solelyfor the purpose of illustration and are not to be construed aslimitations of the present invention, as many variations thereof arepossible without departing from the spirit and scope of the invention.All exemplified concentrations are weight-weight percents, unlessotherwise specified.

Examples 1-3 Water Vapor Source

The water vapor source exemplified below is exothermic heat cells filledwith a particulate exothermic composition for use in the water vaporgenerating portion of the system of the present invention.

The particulate exothermic compositions exemplified below are preparedby using conventional blending techniques to form the particulateexothermic compositions, wherein the resultant compositions provide forthe construction of heat cells of the present invention.

A pre-mix is prepared by adding activated carbon and water into ablender or mixer such as a Littleford Day Mixer, and mixing for aboutten minutes. A polyacrylate absorbent gelling material is then added,and the mixture is mixed for about 10 minutes. Next, sponge iron powderis added to the mixer, and the resultant pre-mix is mixed for about 5minutes.

Approximately 2.2 g of the resultant pre-mix composition are added toeach preformed pocket, which pockets have been created with a vacuum toform the pockets, in a sheet of polypropylene/EVA coextruded film (e.g.60% PP/40% EVA coextruded RMS #GCAS10045989 24.7 gsm 1.4 mil (Clopay,Augusta, Ky.) film).

Next, a brine solution is prepared by adding water, sodium chloride, andoptionally sodium thiosulfate into a mixer and mixing for about fifteenminutes. The resultant brine solution is then rapidly dosed onto thepre-mix composition.

An aerated surface of 100% polypropylene, finished part #CTM4417064,44.1 gsm SMMS (First Quality Nonwovens, McElhattan, Pa.) non-wovenmaterial is placed over the pockets containing the pre-mix and brine,facing the EVA side of the preformed pocket-containing. The film sheetand SMMS are bonded together using a low heat, forming a unifiedstructure. The resulting unified structure contains heat cellscontaining the particulate exothermic composition sealed in the pocketsbetween the opposing surfaces of the aerated surface and the opposedfilm layer surface.

The heat cells begin to generate heat shortly after the brine is addedto the particulate composition, therefore the top and bottom surfacesare bonded and the finished heat cells are quickly packaged in an airtight secondary packaging for future use.

Table 1 illustrates different particulate exothermic compositions ofheat cells of the present invention.

TABLE 1 Particulate Exothermic Compositions Composition CompositionComposition 1 2 3 Component (Wt. %) (Wt. %) (Wt. %) Iron powder (F-417,60.40 56.75 58.70 Hoeganaes Corp., New Jersey) Activated Carbon (NuChar-4.05 3.81 3.94 SN, MeadWestvaco, Covington, VA) Absorbent GellingMaterial 5.09 4.78 4.94 (Sodium polyacrylate, Nippon Shokubai,Chattanooga, TN) Sodium Chloride 3.02 3.47 1.38 Sodium Thiosulfate 0.380.43 — Water 27.06 30.76 31.04

Example embodiments of the present invention are described below withreference to the FIG. 3 and FIG. 1. The same symbols represent the samestructural elements throughout.

FIG. 3 illustrates an embodiment of a moist heat delivery system havingtwo water vapor-air mixing layers and two water vapor-air distributionlayers as part of a water vapor-air regulating portion. Referring toFIG. 3, the water generating portion 110 comprises heat cell 180. Heatcell 180 is constructed according to Example 1 using the Composition ofTable 1 above. Adjacent the water generating portion 110 is a watervapor-air regulating portion 120. Adjacent a second side of the watergenerating portion 110 is the external surface 140 comprising aninsulative layer and an outermost layer.

The heat cell 180 has a particulate exothermic composition dosed in apocket 111 formed in an opposed surface 160 of non-air permeable,non-moisture permeable polypropylene/EVA film layer (e.g. 60% PP/40% EVAcoextruded RMS #GCAS10045989 24.7 gsm 1.4 mil (Clopay, Augusta, Ky.))opposing a polypropylene SMMS (e.g. 100% Polypropylene 34 gsm SB/4 gsmM/4 gsm M/34 gsm SB, Code W502FWH634, 76 gsm (Polymer Group Inc.,Waynesboro, Va.)) aerated surface 170.

The external surface 140 is adjacent to opposed surface 160 andcomprises two layers including a 1/16 inch insulative polypropylene foamlayer 162 (e.g. 100% PP 1/16″MicroFoam RMS #95818584 16 gsm (Pregis,Wurtland, Ky.) and an outermost polypropylene non-woven layer 164.

Adjacent the aerated surface 170 is a 3 mm thick first water vapor-airmixing layer 124 of high loft polyethylene/polyester non-woven batting(e.g. 70% 9 dpfPET/PE BICO/30% 12 dpf hollow PET fibers RMS #95169555 84gsm through air bonded (Libeltex, Meulebeke, Belgium). Adjacent thefirst water vapor-air mixing layer 124 is a first water vapor-airdistribution layer 122 of 1/16 inch thick perforated polypropylene foam(e.g. 100% PP 1/16″ MicroFoam RMS #95818584 16 gsm (Pregis, Wurtland,Ky.); altered internally via cutting dies to add perforation). Adjacentthe first water vapor-air distribution layer 122 is a second 3 mm thickwater vapor-air mixing layer 125 of high loft polyethylene/polyesternon-woven batting of the same material as used in the first water vaporair mixing layer 124. Adjacent the second water vapor-air mixing layer125 is a second water vapor-air distribution layer 123 of 1/16 inchthick perforated polypropylene foam of the same material as used in thefirst water vapor-air distribution layer 122. Attached to the secondwater vapor-air distribution layer 123 is the latent heat deliverysurface 130 comprising two skin-contact layers of polypropylenenon-woven material (e.g. 50/50 Polypropylene/Polyethylene BICO Part#236YLJO09P 80 gsm (Fiberweb, Washougal, Wash.), internally alteredthrough mechanical deformation). The layers are sealed together aroundthe periphery of the layers to form a system.

Referring for FIG. 1, FIG. 1 illustrates an embodiment of a moist heatsystem having only one water vapor-air mixing layer and one watervapor-air distribution layer. Referring to FIG. 1, the heat cell 80 isconstructed according to Example 1 above using the composition ofTable 1. The heat cell 80 has a particulate exothermic water vaporgenerating composition dosed in a pocket 11 formed in an opposed surfaceof polypropylene/EVA (e.g. 60% PP/40% EVA coextruded RMS #GCAS1004598924.7 gsm 1.4 mil (Clopay, Augusta, Ky.)) film layer 60 opposing a 100%polypropylene (i.e. finished part #CTM4417064, 44.1 gsm SMMS (FirstQuality Nonwovens, McElhattan, Pa.) SMMS aerated surface 70.

The external surface 40 is adjacent the opposed surface film layer 60and comprises two layers including a 1/16 inch insulative polypropylenefoam (e.g. MicroFoam RMS #95818584 16 gsm (Pregis, Wurtland, Ky.)) layerand an outer most polypropylene non-woven layer.

Adjacent the aerated surface 70 is the water vapor air mixing layer 24which comprises a 3 mm thick water vapor-air mixing layer 20 of highloft polyethylene/polyester (e.g. 70% 9 dpfPET/PE BICO/30% 12 dpf hollowPET fibers RMS #95169555 84 gsm through air bonded (Libeltex, Meulebeke,Belgium)) non-woven batting. Adjacent the water vapor-air mixing layer24 is a water vapor-air distribution layer 22 of 1/16 inch thickperforated polypropylene foam (e.g. 100% PP 1/16″ MicroFoam RMS#95818584 16 gsm (Pregis, Wurtland, Ky.); altered internally via cuttingdies to add perforation). Adjacent to the water vapor-air distributionlayer 22 is the latent heat delivery surface 30 comprising twoskin-contact layers of polypropylene non-woven material (e.g. 50/50Polypropylene/Polyethylene BICO Part #236YLJ009P 80 gsm (Fiberweb,Washougal, Wash.), internally altered through mechanical deformation).The layers are sealed together around the periphery of the layers toform a system.

Referring to FIG. 4, FIG. 4 is a top plan view of an embodiment of atherapeutic device of the present invention 500 having a plurality ofheat cells (e.g. twenty-four (24) heat cells) 580 forming a water vaporgenerating portion that comprises a particulate exothermic compositionthat includes a water vapor source and a heat source.

IR Imaging Examples

FIGS. 5A and 5B show IR images of an exemplary embodiment of theactivated moist heat delivery system therapeutic device of theinvention. FIG. 5A is a view of the external surface of an activatedmoist heat delivery system therapeutic device of the invention. As FIG.5A shows the outlines of individual heat cells are visible on theexterior surface in the IR image. FIG. 5B is a view of the latent heatdelivery surface of an activated moist heat delivery system therapeuticdevice of the invention. As FIG. 5B shows, the water vapor-airregulating portion facilitates dispersion and uniformity of heat overthe latent heat delivery surface of the activated system. As FIG. 5Bshows, the perimeter shapes of the individual heat cells areindiscernible in an IR image of the latent heat delivery surface of anactivated system that is delivering heat to the latent heat deliverysurface due to dispersion of the heat.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A method of providing a benefit to a usercomprising: (a) providing a portable moist heat delivery systemcomprising a water vapor generating portion comprising a water vaporsource and a heat source; and a water vapor-air regulating portion, saidwater vapor-air regulating portion comprising a water vapor-air mixinglayer, and a water vapor-air distribution layer, said water vaporgenerating portion and said water vapor-air regulating portion being influid communication; and said water vapor-air regulating portion havinga latent heat delivery surface disposed adjacent said water vapor-airregulating portion which delivers moist heat at a preselectedtemperature range; (b) applying said system to a skin surface of a userwherein the latent heat delivery surface is located proximate to saidskin surface of said user; (c) initiating heating of said system; and(d) transferring moist heat to said skin of said user at a preselectedtemperature range, wherein the moist heat is about 15% to about 95%latent heat of condensation.
 2. The method of claim 1 wherein saidportable moist heat system is applied to a skin surface of a human userand wherein said human skin maintains a temperature of less than about43° C. during the transfer of moist heat.
 3. The method of claim 1further comprising the step of providing a skin surface temperature ofat least about 36° C. within about 5minutes of initiation of heating ofsaid system.
 4. The method of claim 1 further comprising the step ofdelivering moist heat to a tissue and providing a temperature of atleast about 38° C., at a depth of at least about 2.5 cm below an outersurface of said skin, within about 60 minutes from initiation of heatingof said system, while maintaining a temperature of said outer surface ofsaid skin of less than about 43° C.
 5. The method of claim 1 whereby themoist heat provides pain relief within about 60 minutes from saidinitiation of heating of said system, while maintaining user skinsurface temperature less than about 43° C.
 6. The method of claim 1further comprising the steps of providing a pain-relieving active; anddelivering said active through said skin.
 7. The method of claim 1providing further comprising the step of generating from about 0.05 mgwater vapor/min/cm2 of water vapor generating portion to about 10 mgwater vapor/min/cm2 of water vapor generating portion; wherein saidwater vapor delivers moisture to the surface of said skin viacondensation onto said surface of the skin, while maintaining skintemperature less than about 43° C.
 8. The method of claim 1 furthercomprising the step of providing a benefit selected from the groupconsisting of reducing cardiac work by at least about 4% during a timeperiod said system is applied to said skin of said user; increasingblood flow, in an area of said skin of said user where said system isapplied; of from about 3 to about 9 times versus blood flow of said areaof skin prior to application of said system; providing relaxation;providing wound healing; providing respiratory relief; providing bodywarming; providing skin hydration; providing enhanced sleep; providingphysical therapy, promoting post-operative recovery, promoting injuryrecovery, enhancing post-operative recovery, enhancing injury recovery,and combinations thereof.